Synthesis of Bis(1,2,3-Triazole) Functionalized Quinoline-2,4-Diones.

Derivatives of 3-(1H-1,2,3-triazol-1-yl)quinoline-2,4(1H,3H)-dione unsubstituted on quinolone nitrogen atom, which are available by the previously described four step synthesis starting from aniline, were exploited as intermediates in obtaining the title compounds. The procedure involves the introduction of propargyl group onto the quinolone nitrogen atom of mentioned intermediates by the reaction of them with propargyl bromide in N,N-dimethylformamide (DMF) in presence of a potassium carbonate and the subsequent formation of a second triazole ring by copper catalyzed cyclisation reaction with azido compounds. The products were characterized by ¹H, 13C and 15N NMR spectroscopy. The corresponding resonances were assigned on the basis of the standard 1D and gradient selected 2D NMR experiments (¹H⁻¹H gs-COSY, ¹H⁻13C gs-HSQC, ¹H⁻13C gs-HMBC) with ¹H⁻15N gs-HMBC as a practical tool to determine 15N NMR chemical shifts at the natural abundance level of 15N isotope.

1. Introduction

The 1,4-disubstituted-1,2,3-triazole heterocyclic motif has become an exceedingly popular structure finding applications in a broad range of areas including materials, biomaterials, metallopharmaceuticals, supramolecular chemistry, chemical sensing and catalysis, to name just a few [1]. In coordination and organometallic chemistry, for example, it became an important ligand scaffold, not only because of simplicity and reliability in its preparation, but also due to a variety of coordination modes offering [2,3,4,5,6]. Owing to the discovery of copper(I)-catalyzed 1,3-cycloaddition of terminal alkynes with organic azides, the CuAAC click reaction, the preparation of 1,4-disubstituted-1,2,3-triazole is facilitated in mild and modular fashion [7,8]. Although this “click triazole” has become a part of a broad range of molecules, its association with quinoline-2,4-diones remains largely underdeveloped. Apart from our recent publication on 3-(1H-1,2,3-triazol-1-yl)quinoline-2,4(1H,3H)-dione derivatives (1, Figure 1) [9], to the best of our knowledge, other 1,2,3-triazole functionalized quinoline-2,4-diones are unprecedented.

Figure 1

A general structure of 1,2,3-triazole quinoline-2,4-diones 1 (left) and the bis(1,2,3-triazole) counterparts 2 (right).

As part of our endeavor in quinoline-2,4-dione chemistry [10] as well as functional n class="Chemical">click triazoles [11,12] and their applications [13], we became interested in the synthesis of bis(1,2,3-triazole) functionalized quinoline-2,4-diones 2 that may potentially serve as functional scaffolds in coordination chemistry, molecular sensing and biochemistry. It is noteworthy that many compounds with the quinoline-2,4-dione structure were isolated from fungi, bacteria and plants, possessing broad range of interesting biological activities in vitro and in vivo [10]. Herein we report an approach to quinoline-2,4-diones unsymmetrically substituted with two click triazoles, an extensive 1H, 13C, and 15N NMR spectral analyses, and a preliminary investigation of their chelating properties towards arene-ruthenium.

2. Results and Discussion

We reasoned that the desired bis(1,2,3-triazole) functionalized n class="Chemical">quinoline-2,4-diones 2 could be obtained via previously described 3-(1H-1,2,3-triazol-1-yl)quinoline-2,4(1H,3H)-dione derivatives 1 as synthetic intermediates (Scheme 1). The latter were prepared in a four-step reaction sequence starting from aniline, which upon treatment with diethyl 2-methylmalonate and diethyl 2-phenylmalonate initially afforded the corresponding 4-hydroxyquinolin-2(1H)-ones 3a and 3b [14]. Chlorination with sulfuryl chloride into 3-methyl- and 3-phenyl-3-chloroquinolin-2,4(1H,3H)-diones 4a [15] and 4b [16], followed by the nucleophilic displacement of the chlorine atoms with sodium azide, gave 3-methyl- and 3-phenyl- substituted 3-azidoquinoline-2,4(1H,3H)-diones 5a and 5b [16]. Then we began with copper-catalyzed azide-alkyne cycloaddition reaction (CuAAC).

Scheme 1

Preparation of bis(1,2,3-triazole) functionalized quinoline-2,4-diones 2.

Although a large variety of reaction conditions have been developed for the CuAAC reaction [17,18], our previous work in this field has shown that for n class="Chemical">3-azidoquinoline-2,4(1H,3H)-diones a combination of copper(II) sulfate pentahydrate and elemental copper (CuSO4/Cu0) in dimethyl sulfoxide (DMSO) provided results that were superior to other combinations. Adopting those previous results in this work some additional optimizations of the reaction conditions were carried out with 5a and phenylacetylene (6a) as the model substrates. Screening through the reaction solvents indicated that N,N-dimethylformamide (DMF) is even more efficient than DMSO, providing the desired target compound 1a in shorter reaction times. The influence of the amount of granular copper to the course of the reaction between 5a and equimolar amount of 6a in DMF was also briefly investigated. While keeping the loading of CuSO4·5H2O constant at 10 mol % relative to 5a, the amount of the elemental copper was varied from 380 mol % to 100 mol %. The results are summarized in Table 1.

Table 1

The Effect of Granular Copper to the Conversion of 5a into 1a a.

Entry	Cu0 (mmol)	Reaction Time (h)	Yield b (%)
1	3.8	0.75	98
2	3	0.75	91
3	2	1	89
4	1	25	82 c

a Reaction conditions: 5a (1 mmol), phenylacetylene (1 mmol), and CuSO4·5H2O (0.1 mmol), DMF (4 mL), rt. The reaction time was determined by thin-layer chromatography (TLC) monitoring of the reaction mixture. b Refers to the yield of isolated pure product. c Complete consumption of 5a was not reached.

Based on the above, in a general procedure, a mixture of 3-azidoquinoline-2,4(1H,3H)-dione (5, 1.0 mmol), a slight excess of terminal n class="Chemical">alkyne 6 (1.05 mmol), CuSO4⋅5H2O (0.12 mmol), and granular copper (2.0 mmol) in DMF (2.3 mL) was stirred at room temperature, in the presence of air. In addition to phenylacetylene (6a), propargyl alcohol (6b) was selected as the acetylene partner. The reactions were completed within 30 min. As indicated in Table 2, the products 1 were obtained in excellent yields. By using a more standard CuSO4∙5H2O/l-ascorbic acid catalyst in CH2Cl2/water biphasic system, the cycloaddition between 5a and 6a required substantially longer reaction time (48 h) to achieve a similar yield of the product 1a as compared to the above CuSO4/Cu0/DMF conditions (Entries 1 and 2).

Table 2

Preparation of compounds 1.

Entry	Azide 5	R1	Acetylene 6	R2	Product 1	Yield a
1	5a	Me	6a	Ph	1a	95
2	5a	Me	6a	Ph	1a	83 b
3	5b	Ph	6a	Ph	1b	86
4	5a	Me	6b	CH2OH	1c	99
5	5b	Ph	6b	CH2OH	1d	98

a Refers to percent yield of pure (by TLC and IR) isolated product. b Employing CuSO4∙5H2O/l-ascorbic acid/CH2Cl2/water conditions, 48 h reaction time.

Prior to the introduction of propargyl group at the N1 n class="Chemical">nitrogen atom of the quinoline-2,4(1H,3H)-dione ring in 1, the primary hydroxyl groups at 1c and 1d were protected by acetylation by using acetic anhydride in pyridine as shown in Scheme 2. The corresponding acetates 1e and 1f were obtained in 84–85% yields.

Scheme 2

Preparation of compounds 1e and 1f.

Alkylation of compounds 1a,b,e,f with propargyl group was carried out by using 1.5 equivalent of propargyl bromide (n class="Chemical">6c) and 3 equivalents of potassium carbonate in DMF. These reactions proceeded smoothly within 45 min at room temperature. The yields are given in Table 3.

Table 3

Preparation of compounds 7.

Entry	1	R1	R2	6	Yield of 7 (%) a
1	1a	Me	Ph	6c	7a, 96
2	1b	Ph	Ph	6c	7b, 79
3	1e	Me	CH2OAc	6c	7c, 81
4	1f	Ph	CH2OAc	6c	7d, 63

a Refers to percent yield of pure (by TLC and IR) isolated product.

Although N-alkylation of the n class="Chemical">lactam group usually takes place preferentially in quinoline-2,4(1H,3H)-diones [10], the competitive O-alkylation has been documented in similar systems [19]. The N1 position of thus introduced propargyl group in 7 was confirmed by 2D NMR spectroscopy in particular by the presence of the long-range correlations between the propargyl methylene protons and carbon atoms C-8a and C-2 in the 1H-13C HMBC spectra (in 7a,c,d) as well as N1 nitrogen atom in the 1H–15N gs-HMBC spectrum (in 7a).

As the last step of the reaction sequence shown in Scheme 1, monotriazoles 7 were submitted to a second cycloaddition with selected n class="Chemical">azides 8 to give the expected bis-triazoles 2. Benzyl azide (8a), azidobenzene (8b) and tetrazolo[1,5-a]pyridine (8c) were selected as the reaction partners. Whereas benzyl azide (8a) and azidobenzene (8b) readily reacted into the desired products 2a,b,d,e,g,h,j,k at room temperature, tetrazolo[1,5-a]pyridine (8c), a synthetic equivalent for 2-azidopyridine (8c’), required harsher reaction conditions (Table 4). This can be explained by the tetrazolyl form in which compound 8c exists predominantly at room temperature [11]. As the proportion of the azido isomer increases at elevated temperature, the reactions with 8c were conducted at 100 °C, to afford compounds 2c,f,i,l in good yields.

Table 4

Preparation of compounds 2.

Entry	2	R1	R2	R3	t (°C)	Time (h)	Yield a (%)
1	a	Me	Ph	Bn	23	1	97
2	b	Me	Ph	Ph	23	1	99
3	c	Me	Ph	2-Py	100	0.5	93
4	d	Me	CH2OAc	Bn	23	0.5	96
5	d	Me	CH2OAc	Bn	23	4	85 b
6	d	Me	CH2OAc	Bn	23	48	81 c
7	d	Me	CH2OAc	Bn	23	45	45 d
8	e	Me	CH2OAc	Ph	23	2	92
9	f	Me	CH2OAc	2-Py	100	1	85
10	g	Ph	Ph	Bn	23	1	92
11	h	Ph	Ph	Ph	23	1	94
12	i	Ph	Ph	2-Py	100	0.75	57
13	j	Ph	CH2OAc	Bn	23	2	97
14	k	Ph	CH2OAc	Ph	23	0.5	93
15	l	Ph	CH2OAc	2-Py	100	0.5	85

a Refers to percent yield of pure (by TLC and IR) isolated product. b Employing CH2Cl2/water/CuSO4∙5H2O/Na-ascorbate conditions. c Employing t-BuOH/water/CH3CN/CuSO4∙5H2O/Na-ascorbate conditions. d Employing t-BuOH/water/CuSO4∙5H2O/l-ascorbic acid conditions.

In this case too, some standard click catalyst/solvent combinations were briefly evaluated. The cycloaddition between n class="Chemical">acetylene 7c and benzyl azide (8a) with CuSO4∙5H2O/Na-ascorbate (or l-ascorbic acid) pair in CH2Cl2/water and t-BuOH/water solvent systems required prolonged reaction times, providing lower yields of the product 2d as compared to the CuSO4/Cu0/DMF conditions (compare Entries 4–7). In the case of t-BuOH/water the presence of water in the reaction mixture turned the reactants and products into a gummy material that stuck to the reaction vessel and the magnetic stirring bar, impeding the reaction from going to completion, as already noticed for click reactions with highly hydrophobic reagents [20].

In principle, the “click-propargylation-n class="Chemical">click” reaction sequence at 3-azidoquinoline-2,4-diones 5 could be altered, providing the target bis-(1,2,3-triazole) functionalized products 2 via bifunctional azidoethynyl quinoline-2,4-dione intermediate 9 as shown in Scheme 3. This would allow orthogonal sequential synthetic strategies for accessing bis(1,2,3-triazole) functionalized materials [21]. We briefly explored this possibility by treating 3-azido-1-propargylquinoline-2,4-dione derivative 9a with phenylacetylene (6a) or benzyl azide (8a) under the above mentioned CuSO4/Cu0/DMF conditions. The corresponding monotriazoles 7a (16%) and 10a (42%), respectively, were obtained in moderate yields.

Scheme 3

An alternative approach to bis(1,2,3-triazole) functionalized quinoline-2,4-diones 2 through a “propargylation-click-click” reaction sequence.

The compounds 2a–l were characterized by 1H, n class="Chemical">13C and, with the exception of 2a,g,h, also by 15N NMR spectroscopy. The corresponding resonances were assigned on the basis of gradient-selected 2D NMR experiments including 1H–1H gs-COSY, 1H–13C gs-HSQC, 1H–13C gs-HMBC and 1H–15N gs-HMBC. For the atom numbering scheme, see Figure 2. Some characteristic spectral features are discussed below.

Figure 2

Selected ring and atom numbering along with the chemical shift data (mean values rounded up to whole numbers are provided).

The 13C and n class="Chemical">15N chemical shifts for triazole rings A and D (Table 5 and Table 6) are in a good agreement with those reported previously [11].

Table 5

Selected 1H, 13C and 15N NMR chemical shifts in ppm for compounds 1 and 7.

	1a	1b	1c	1d	7a	7b	7c	7d
Quinolone
N1	–	–	–	–	–	–	134.4	–
C2	168.5	166.8	168.7	166.8	167.7	165.8	167.8	165.8
C3	72.2	80.0	71.9	79.7	72.6	79.6	72.8	80.0
C4	190.7	188.9	190.8	189.0	189.7	187.5	189.6	187.7
C4a	117.4	119.2	117.5	119.2	119.0	121.0	119.2	120.9
C5	127.7	127.6	127.6	127.5	128.2	129.2	128.0	127.8
C6	123.5	123.5	123.3	123.4	124.2	124.6	124.0	124.2
C7	137.3	137.0	137.1	136.9	137.3	136.9	137.1	136.7
C8	117.0	116.7	116.9	116.7	116.7	115.8	116.6	116.3
C8a	141.6	140.5	141.6	140.6	140.8	140.6	140.7	140.0
Ring A
N1A	–	–	–	–	–	–	247.9	–
N2A	–	–	–	–	–	–	363.4	–
N3A	–	–	–	–	–	–	354.0	–
C4A	145.8	145.3	147.4	146.8	145.9	146.0	141.5	140.9
C5A	122.4	123.4	123.7	124.8	122.5	122.3	126.0	127.1
H5A	8.89	8.49	8.26	7.77	8.89	7.26	8.46	8.15

Table 6

Selected 1H, 13C and 15N NMR chemical shifts in ppm for compounds 2.

	2a	2b	2c	2d	2e	2f	2g	2h	2i	2j	2k	2l
Quinolone
N1	–	136.3	135.8	138.7	138.7	135.3	–	–	137.5	140.4	140.4	138.9
C2	168.2	168.3	168.5	168.2	168.3	168.6	166.2	166.4	166.6	166.6	166.9	166.6
C3	72.8	73.0	73.0	71.6	71.5	73.3	80.1	80.3	80.4	79.6	79.6	79.7
C4	190.0	190.0	189.9	189.4	189.4	189.9	188.2	188.2	188.1	187.9	187.9	187.9
C4a	119.1	119.2	119.3	119.2	119.2	119.4	120.9	120.9	120.9	120.9	120.9	121.0
C5	128.1	128.1	128.1	129.3	129.4	127.9	127.9	127.9	127.9	129.0	129.1	129.1
C6	123.9	124.0	123.9	124.6	124.7	123.8	124.0	124.1	124.0	124.6	124.7	124.6
C7	137.2	137.3	137.2	137.8	137.8	137.0	136.8	136.8	136.8	137.2	137.4	137.2
C8	116.7	116.8	116.6	116.9	116.8	116.5	116.7	116.7	116.5	116.8	116.7	116.6
C8a	141.5	141.6	141.4	141.7	141.7	141.3	140.8	140.7	140.5	141.1	140.9	141.2
Ring A
N1A	–	248.9	248.9	248.4	248.8	247.6	–	–	248.7	249.8	249.9	249.7
N2A	–	363.2	363.4	361.6	–	363.7	–	–	367.4	365.1	–	–
N3A	–	347.1	347.1	355.2	355.5	353.4	–	–	347.2	356.9	357.2	357.1
C4A	145.9	146.0	146.0	142.3	142.3	141.6	145.4	145.4	145.4	140.9	140.9	140.9
C5A	122.5	122.5	122.5	124.2	124.1	126.1	123.4	123.5	123.4	126.4	126.4	126.4
H5A	8.87	8.87	8.87	7.78	7.86	8.47	8.51	8.54	8.58	7.08	7.14	7.13
Ring D
N1D	–	255.7	260.5	250.4	256.3	260.0	–	–	260.4	250.4	256.3	261.2
N2D	–	358.1	358.6	362.6	–	361.9	–	–	–	362.9	–	–
N3D	–	353.4	356.9	350.0	351.9	356.5	–	–	357.7	350.5	352.9	355.8
C4D	142.2	143.3	143.2	142.9	143.2	143.2	141.9	142.9	143.0	142.9	143.2	143.0
C5D	123.8	121.8	120.6	123.5	121.7	120.6	124.2	122.3	120.8	123.5	121.8	121.0
H5D	8.16	8.75	8.82	7.55	8.10	8.82	8.24	8.83	8.81	7.58	8.05	8.63

To preliminarily assess the applicability of bis-triazole compounds 2 as ligands, we decided to examine their coordination abilities to n class="Chemical">arene-ruthenium. NMR experiment was designed in which compound 2b and equimolar amount of ruthenium (0.5 equiv of [RuCl(μ-Cl)(η6-p-cymene)]2) were mixed in CDCl3 in NMR tube at room temperature. CDCl3 was selected as the reaction solvent in place of the coordinative DMSO-d6 to avoid possible interference with the metal center (Scheme 4). The reaction mixture was monitored by time dependent 1H NMR spectroscopy indicating an instant change in the resonances for 2b and p-cymene ligands upon mixing to form a new set of resonances that remained unchanged over several days. As shown in Figure 3 and Figure 4, both proton and carbon NMR resonances were severely broadened suggesting the presence of a dynamic process in the solution, presumably an equilibrium with the starting ligand, which can result from a relatively weak ligand-to-metal interaction. Unfortunately, broad NMR resonances prevented an unambiguous structure determination of the product [Ru–Cym]-2b through the 2D NMR techniques due to overlap as well as lack of several indicative crosspeaks in the spectra, especially in 1H–15N gs-HMBC. Nevertheless, the analysis of the available NMR data tentatively suggested the coordination of both 1,2,3-triazole rings to the Ru–Cym unit as indicated in Scheme 4. Although the coordination properties of the 1,2,3-triazole nitrogen atom N2 are weak, some of us have previously shown that such chelates can be greatly stabilized through an assistance of auxiliary ligand [22].

Scheme 4

Reaction of 2b with [RuCl(μ-Cl)(η6-p-cymene)]2 with tentatively proposed structure of the [Ru–Cym]-2b complex.

Figure 3

Aromatic region of 1H NMR spectra of: (a) 2b in CDCl3, and (b) a mixture of 2b (42 mM) and [RuCl(μ-Cl)(η6-p-cymene)]2 (21 mM) in CDCl3 immediately after dissolution.

Figure 4

Aromatic region of 13C NMR spectra of: (a) 2b in CDCl3, and (b) a mixture of 2b (42 mM) and [RuCl(μ-Cl)(η6-p-cymene)]2 (21 mM) in CDCl3.

Attempts to unambiguously determine the structure of [Ru–Cym]-2b by variable temperature NMR techniques, as well as to grow crystals suitable for X-ray, failed. All of the above also applies to compounds 2g and n class="Chemical">2h that were also preliminarily tested in [Ru–Cym] coordination.

3. Materials and Methods

3.1. General Experimental Methods

The reagents and solvents were used as obtained from the commercial sources. Compounds 3a [14], 3b [14], and 5b [15], as well as benzyl azide (8a) [23], n class="Chemical">azidobenzene (8b) [11], and tetrazolo[1,5-a]pyridine (8c) [24] were prepared as described in the literature. Column chromatography was carried out on Fluka Silica gel 60 (particle size 0.063–0.2 mm, activity acc. Brockmann and Schodder 2–3). Melting points were determined on the microscope hot stage, Kofler, PolyTherm, manufacturer Helmut Hund GmbH, Wetzlar and are uncorrected. TLC was carried out on pre-coated TLC sheets ALUGRAM® SIL G/UV254 for TLC, MACHEREY-NAGEL. NMR spectra were recorded with a Bruker Avance III 500 MHz NMR instrument operating at 500 MHz (1H), 126 MHz (13C) and 51 MHz (15N) at 300 K. Proton spectra were referenced to TMS as internal standard, in some cases to the residual signal of DMSO-d5 (at δ 2.50 ppm) or CHCl3 (at δ 7.26 ppm). Carbon chemical shifts were determined relative to the 13C signal of DMSO-d6 (39.52 ppm) or CDCl3 (77.16 ppm). 15N chemical shifts were extracted from 1H–15N gs-HMBC spectra (with 20 Hz digital resolution in the indirect dimension and the parameters adjusted for a long-range 1H–15N coupling constant of 5 Hz) determined with respect to external nitromethane and are corrected to external ammonia by addition of 380.5 ppm. Nitrogen chemical shifts are reported to one decimal place as measured of the spectrum, however, the data should not be considered to be more accurate than ±0.5 ppm because of the digital resolution limits of the experiment. Chemical shifts are given on the δ scale (ppm). Coupling constants (J) are given in Hz. Multiplicities are indicated as follows: s (singlet), d (doublet), t (triplet), q (quartet), m (multiplet) or br (broadened). Infrared spectra were recorded on FT-IR spectrometer Alpha (Bruker Optik GmbH Ettlingen, Ettlingen, Germany) using samples in potassium bromide disks and only the strongest/structurally most important peaks are listed. Electron impact mass spectra (EI) were recorded on a Shimadzu QP–2010 instrument at 70 eV. HRMS spectra were recorded with Agilent 6224 Accurate Mass TOF LC/MS system with electrospray ionization (ESI). Elemental analyses (C, H, N) were performed with FlashEA1112 Automatic Elemental Analyser (Thermo Fisher Scientific Inc., Waltham, MA, USA).

3.2. General Procedure for the Synthesis of 3-Chloroquinoline-2,4(1H,3H)-Diones 4 (Scheme 1)

The 3-Chloroquinoline-2,4(1H,3H)-diones 4a [15] and 4b [16], were prepared from 4‑hydroxyquinolin-2(n class="Chemical">1H)-ones 3a [14] and 3b [14], respectively, according to the procedures described in the literature.

3-Chloro-3-methyln class="Chemical">quinoline-2,4(1 Compound 4a (19.71 g, 94.0 mmol, 94%) was prepared from 3a (17.52 g, 100 mmol). Yellow crystals, m.p. 178–181 °C (benzene), m.p. [15] 172 °C (acetic acid—water); Rf = 0.52 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3) δ 1.99 (s, 3H), 7.06 (d, 1H, J = 8.0 Hz), 7.22 (dd, 1H, J = 7.6, 7.6 Hz), 7.59–7.66 (m, 1H), 8.02 (d, 1H, J = 7.7 Hz), 9.41 (s, 1H); 13C NMR (126 MHz, CDCl3) δ 21.2, 62.8, 116.7, 118.1, 124.5, 129.1, 136.8, 139.6, 169.2, 188.4; IR (cm−1): ν 3203, 3072, 3004, 2940, 1709, 1674, 1614, 1600, 1486, 1439, 1379, 1239, 770, 440; MS (EI) m/z (%): 212 (4, [M + 3]+), 211 (33, [M (37Cl)]+), 210 (17, [M + 1]+), 209 (100, [M (35Cl)]+), 208 (18), 175 (15), 174 (36), 146 (68), 128 (17), 120 (18), 119 (59), 92 (32), 91 (15); HRMS (ESI+): m/z calcd for C10H9ClNO2+ [M + H]+ 210.0316, found 210.0313. Anal. Calcd for C10H8ClNO2 (209.63): C, 57.30; H, 3.85; N, 6.68%. Found: C, 57.18; H, 3.83; N, 6.61%.

3-Chloro-3-phenyln class="Chemical">quinoline-2,4(1 Compound 4b (26.08 g, 96.0 mmol, 96%) was prepared from 3b (23.73 g, 100 mmol). Pale yellow needles, m.p. 182–185 °C (benzene), m.p. [16] 178–180 °C (ethanol); Rf = 0.57 (30% ethyl acetate in chloroform). 1H NMR (500 MHz, CDCl3) δ 7.04 (d, 1H, J = 8.0 Hz, H-8), 7.18 (ddd, 1H, J = 7.8, 7.4, 0.7 Hz, H-6), 7.33–7.39 (m, 3H, H‑3C, H‑4C, H‑5C), 7.51–7.54 (m, 2H, H-2C, H-6C), 7.55 (ddd, 1H, J = 7.3, 6.5, 1.5 Hz, H-7), 7.97 (dd, 1H, J = 7.8, 1.2 Hz, H-5), 9.82 (s, 1H, H-1); 13C NMR (126 MHz, CDCl3) δ 74.9 (C-3), 116.9 (C-8), 118.7 (C-4a), 124.7 (C-6), 127.4 (C-2C, C-6C), 129.1 (C-5), 129.2 (C-3C, C-5C), 129.8 (C-4C), 134.6 (C-1C), 137.0 (C-7), 139.4 (C-8a), 168.8 (C-2), 187.9 (C-4); IR (cm−1): ν 3201, 3138, 3082, 2992, 2926, 1716, 1680, 1613, 1595, 1485, 1365, 755, 743, 690; MS (EI) m/z (%): 273 (7, [M (37Cl)]+), 271 (21, [M (35Cl)]+), 238 (12), 237 (80), 236 (100), 218 (10), 120 (63), 119 (19), 92 (34), 89 (10), 77 (12), 76 (10), 65 (14), 63 (10); HRMS (ESI+): m/z calcd for C15H11ClNO2+ [M + H]+ 272.0473, found 272.0480. Anal. Calcd for C15H10ClNO2 (271.70): C, 66.31; H, 3.71; N, 5.16%. Found: C, 66.07; H, 3.62; N, 5.29%.

3.3. General Procedure for the Synthesis of 3-Azidoquinoline-2,4(1H,3H)-Diones 5 (Scheme 1)

To a stirred solution of the 3-chloroquinoline-2,4(1H,3H)-dione 4 (40 mmol) in n class="Chemical">DMF (200 mL), sodium azide (3.90 g, 60 mmol) was added in small portions during 10 min. The reaction mixture was stirred in darkness for additional 2 h and then poured into ice-water (1.5 L). The precipitated solid was filtered, washed with water and dried at 50 °C in darkness, which afforded product 5, pure according to TLC and 1H NMR spectrum, which was crystallized from benzene.

3-Azido-n class="Chemical">3-methylquinoline-2,4(1 Compound 5a (8.47 g, 39.2 mmol, 98%) was prepared from 4a (8.39 g, 40.0 mmol). Colorless needles, m.p. 158–161 °C (benzene, 87% yield of recrystallization); Rf = 0.30 (30% ethyl acetate in chloroform). 1H NMR (500 MHz, CDCl3) δ 1.86 (s, 3H, CH3), 7.11 (d, 1H, J = 8.0 Hz, H-8), 7.22 (dd, 1H, J = 7.4, 7.4 Hz, H-6), 7.60–7.67 (m, 1H, H-7), 7.98 (d, 1H, J = 7.3 Hz, H-5), 9.86 (s, 1H, H-1); 13C NMR (126 MHz, CDCl3) δ 23.6 (CH3), 70.0 (C-3), 116.9 (C-8), 118.0 (C-4a), 124.6 (C-6), 128.6 (C-5), 137.2 (C-7), 140.0 (C-8a), 171.6 (C-2), 191.7 (C-4); IR (cm−1): ν 3202, 3078, 3005, 2936, 2108, 1708, 1682, 1614, 1598, 1485, 1392, 1284, 1156, 755, 612; MS (EI) m/z (%): 217 (0.24, [M + 1]+), 216 (2, [M]+), 147 (15), 120 (11), 119 (100), 92 (35), 91 (11), 64 (12); HRMS (ESI+): m/z calcd for C10H9N4O2+ [M + H]+ 217.0720, found 217.0724. Anal. Calcd for C10H8N4O2 (216.20): C, 55.55; H, 3.73; N, 25.91%. Found: C, 55.44; H, 3.72; N, 25.98%.

3-Azido-3-n class="Chemical">phenylquinoline-2,4(1 Compound 5b (10.90 g, 39.2 mmol, 98%) was prepared from 4b (10.87 g, 40.0 mmol). Colorless needles, m.p. 186–189 °C (benzene, 96% yield of recrystallization); m.p. [9] 173–181 °C (benzene); Rf = 0.33 (38% ethyl acetate in petroleum ether); 1H NMR (500 MHz, CDCl3) δ 6.98 (d, 1H, J = 8.1 Hz, H-8), 7.16 (dd, 1H, J = 7.6, 7.6 Hz, H-6), 7.38–7.43 (m, 3H, H-3C, H-4C, H-5C), 7.48–7.53 (m, 2H, H-2C, H-6C), 7.54 (ddd, 1H, J = 7.7, 7.7, 1.6 Hz, H-7), 7.93 (dd, 1H, J = 7.8, 1.6 Hz, H-5), 9.30 (s, 1H, H-1); 13C NMR (126 MHz, CDCl3) δ 78.0 (C-3), 116.7 (C-8), 119.5 (C-4a), 124.6 (C-6), 127.3 (C-2C, C-6C), 128.6 (C-5), 129.8 (C-3C, C-5C), 130.4 (C-4C), 132.6 (C-1C), 136.9 (C-7), 139.4 (C-8a), 170.2 (C-2), 189.9 (C-4); 15N NMR (51 MHz, CDCl3) δ 133.4 (N-1); IR (cm−1): ν 3244, 2105, 1718, 1705, 1685, 1611, 1484, 1356, 1256, 877, 773, 744, 702, 611, 525; MS (EI) m/z (%): 250 (7, [M − N2]+), 236 (8, [M − N3]+), 147 (28), 120 (14), 119 (100), 104 (15), 92 (32), 77 (10), 76 (10), 64 (14); HRMS (ESI+): m/z calcd for C15H11N2O2+ [M − N2 + H]+ 251.0815, found 251.0818. HRMS (ESI−): m/z calcd for C15H9N4O2− [M − H]− 277.0731, found 277.0732; calcd for C15H9N2O2− [M − N2 − H]− 249.0670, found 249.0671. Anal. Calcd for C15H10N4O2 (278.27): C, 64.74; H, 3.62; N, 20.13%. Found: C, 64.54; H, 3.56; N, 20.38%.

3.4. General Procedure for the Synthesis of 3-(1H-1,2,3-Triazol-1-yl)Quinoline-2,4(1H,3H)-Diones 1a–d by Employing CuSO4/Cu0/DMF Conditions (Table 2, Entries 1 and 3–5)

A solution of phenylacetylene (6a) (1.287 g, 12.6 mmol) or n class="Chemical">propargyl alcohol (6b) (706 mg, 12.6 mmol) in DMF (4 mL) was added dropwise to a vigorously stirred mixture of 3-azidoquinoline-2,4(1H,3H)-dione 5 (12 mmol), CuSO4⋅5H2O (300 mg, 1.2 mmol), granular copper (1.5 g, 24 mmol) and DMF (24 mL). The reaction mixture was stirred in darkness for 30 min. Afterward, (NH4)2CO3 (3.5 g, 36 mmol) and water (12 mL) were added to the resulting brown-black suspension and the stirring was continued for 10 min. The reaction mixture was subjected to column chromatography with silica gel (15 g, column diameter of 1 cm) as a stationary phase, and 10% ethanol in chloroform as a mobile phase. Combined fractions containing yellow eluate were washed with saturated aqueous NH4Cl (5 × 50 mL), dried (Na2SO4), and concentrated under reduced pressure to afford pure products 1a–d, which were recrystallized from ethanol for analyses.

3-Methyl-3-(4-n class="Chemical">phenyl-1 Colorless solid, m.p. 217–219 °C (ethanol); Rf = 0.35 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d) δ 2.15 (s, 3H, CH3), 7.22–7.27 (m, 2H, H-6, H-8), 7.33–7.39 (m, 1H, H-4B), 7.45–7.50 (m, 2H, H-3B, H-5B), 7.73–7.79 (m, 1H, H-7), 7.83–7.90 (m, 3H, H-5, H-2B, H-6B), 8.89 (s, 1H, H-5A), 11.48 (s, 1H, H-1); 13C NMR (126 MHz, DMSO-d) δ 23.1 (CH3), 72.2 (C-3), 117.0 (C-8), 117.4 (C-4a), 122.4 (C-5A), 123.5 (C-6), 125.1 (C-2B, C-6B), 127.7 (C-5), 128.0 (C-4B), 129.0 (C-3B, C-5B), 130.6 (C-1B), 137.3 (C-7), 141.6 (C-8a), 145.8 (C-4A), 168.5 (C-2), 190.7 (C-4); IR (cm−1): ν 3137, 2911, 1714, 1683, 1612, 1483, 1430, 1386, 1355, 1238, 1023, 808, 759, 690, 594; MS (EI) m/z (%): 319 (2, [M + 1]+), 318 (8, [M]+), 117 (14), 116 (100), 102 (12), 89 (14); HRMS (ESI+): m/z calcd for C18H15N4O2+ [M + H]+ 319.1190, found 319.1188. Anal. Calcd for C18H14N4O2 (318.33): C, 67.91; H, 4.43; N, 17.60%. Found: C, 67.80; H, 4.47; N, 17.89%.

3-Phenyl-3-(4-n class="Chemical">phenyl-1 Colorless solid, m.p. 280–283 °C (ethanol); m.p. [9] 274–277 °C (ethanol); Rf = 0.37 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d) δ 7.12 (d, 1H, J = 8.1 Hz, H-8), 7.16–7.20 (m, 1H, H-6), 7.31–7.37 (m, 1H, H-4B), 7.40–7.47 (m, 4H, H-3B, H-5B, H-2C, H-6C), 7.49–7.55 (m, 3H, H-3C, H-4C, H-5C), 7.62–7.67 (m, 1H, H-7), 7.80–7.84 (m, 2H, H-2B, H-6B), 7.86 (dd, 1H, J = 7.8, 1.4 Hz, H-5), 8.49 (s, 1H, H-5A), 11.68 (s, 1H, H-1); 13C NMR (126 MHz, DMSO-d) δ 80.0 (C-3), 116.7 (C-8), 119.2 (C-4a), 123.4 (C-5A), 123.5 (C-6), 125.2 (C-2B, C-6B), 127.6 (C-5), 128.0 (C-4B), 128.9 (C-2C, C-6C), 129.0 (C-3B, C-5B), 129.6 (C-3C, C-5C), 129.9 (C-1C), 130.5 (C-1B), 130.6 (C-4C), 137.0 (C-7), 140.5 (C-8a), 145.3 (C-4A), 166.8 (C-2), 188.9 (C-4); IR (cm−1): ν 3275, 3169, 1721, 1690, 1613, 1595, 1486, 1452, 1353, 854, 771, 756, 699, 666, 607; MS (EI) m/z (%): 381 (2, [M + 1]+), 380 (8, [M]+), 247 (13), 237 (15), 236 (56), 220 (13), 218 (13), 120 (11), 117 (10), 116 (100), 102 (15), 92 (10), 89 (15), 77 (14); HRMS (ESI+): m/z calcd for C23H17N4O2+ [M + H]+ 381.1346, found 381.1341. Anal. Calcd for C23H16N4O2 (380.40): C, 72.62; H, 4.24; N, 14.73%. Found: C, 72.40; H, 4.23; N, 14.90%.

3-(4-(Hydroxymethyl)-1 Colorless solid, m.p. 188–189 °C (ethanol); Rf = 0.35 (30% n class="Chemical">ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.08 (s, 3H, CH3), 4.55 (d, 2H, J = 5.6 Hz, CH2), 5.28 (t, 1H, J = 5.6 Hz, OH), 7.18–7.25 (m, 2H, H-6, H-8), 7.69–7.76 (m, 1H, H-7), 7.83 (dd, 1H, J = 8.1, 1.4 Hz, H-5), 8.26 (s, 1H, H-5A), 11.39 (s, 1H, H-1); 13C NMR (126 MHz, DMSO-d6) δ 23.1 (CH3), 55.0 (CH2), 71.9 (C-3), 116.9 (C-8), 117.5 (C-4a), 123.3 (C-6), 123.7 (C-5A), 127.6 (C-5), 137.1 (C-7), 141.6 (C-8a), 147.4 (C-4A), 168.7 (C-2), 190.8 (C-4); IR (cm−1): ν 3148, 2992, 2919, 1729, 1682, 1613, 1486, 1378, 1345, 1235, 1189, 1009, 751, 667, 590; MS (EI) m/z (%): 273 (2, [M + 1]+), 272 (13, [M]+), 185 (68), 175 (89), 174 (45), 146 (100), 128 (58), 120 (70), 119 (75), 92 (66), 91 (39), 77 (39), 65 (37), 55 (39), 42 (79); HRMS (ESI+): m/z calcd for C13H13N4O3+ [M + H]+ 273.0982, found 273.0981. Anal. Calcd for C13H12N4O3 (272.26): C, 57.35; H, 4.44; N, 20.58%. Found: C, 57.20; H, 4.42; N, 20.83%.

3-(4-(Hydroxymethyl)-1 Colorless solid, m.p. 139–143 °C (ethanol); m.p. [9] 116–135 °C (n class="Chemical">benzene); Rf = 0.27 (10% ethanol in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 4.53 (d, 2H, J = 5.7 Hz, CH2), 5.22 (t, 1H, J = 5.7 Hz, OH), 7.09 (d, 1H, J = 8.1 Hz, H-8), 7.13–7.18 (m, 1H, H-6), 7.36–7.42 (m, 2H, H-2C, H-6C), 7.47–7.53 (m, 3H, H-3C, H-4C, H-5C), 7.59–7.65 (m, 1H, H-7), 7.77 (s, 1H, H-5A), 7.83 (dd, 1H, J = 7.8, 1.3 Hz, H-5), 11.60 (s, 1H, H-1); 13C NMR (126 MHz, DMSO-d6) δ 55.0 (CH2), 79.7 (C-3), 116.7 (C-8), 119.2 (C-4a), 123.4 (C-6), 124.8 (C-5A), 127.5 (C-5), 128.8 (C-2C, C-6C), 129.6 (C-3C, C-5 C), 130.2 (C-1C), 130.5 (C-4C), 136.9 (C-7), 140.6 (C-8a), 146.8 (C-4A), 166.8 (C-2), 189.0 (C-4); IR (cm−1): ν 3392, 3136, 2926, 1724, 1692, 1654, 1613, 1485, 1438, 1353, 857, 769, 752, 665, 603; MS (EI) m/z (%): 335 (0.8, [M + 1]+), 334 (4, [M]+), 305 (37), 275 (18), 249 (30), 247 (27), 237 (50), 236 (100), 218 (35), 208 (18), 180 (20), 120 (33), 104 (23), 92 (23), 77 (34); HRMS (ESI+): m/z calcd for C18H15N4O3+ [M + H]+ 335.1139, found 335.1138. Anal. Calcd for C21H21N5O4 (407.42): C, 61.91; H, 5.20; N, 17.19%. Found: C, 61.89; H, 5.24; N, 17.28%.

3.5. Synthesis of Compound by Employing CuSO4∙5H2O/l-Ascorbic Acid/CH2Cl2/Water Conditions (Table 2, Entry 2)

To a solution of azide 5a (162 mg, 0.75 mmol) and n class="Chemical">phenylacetylene (6a) (153 mg, 1.5 mmol) in dichloromethane (8 mL) a solution of l-ascorbic acid (106 mg, 0.60 mmol) in water (4 mL), and a solution of CuSO4∙5H2O (15 mg, 0.06 mmol) in water (4mL) were added. The two-phase reaction mixture was stirred in darkness at room temperature for 48 h. The reaction mixture was extracted with chloroform (5 × 30 mL). The combined organic layers were dried (Na2SO4), filtered, and evaporated to dryness. The residue was dissolved in chloroform (5 mL) and subjected to silica gel (30 g) column chromatography using 38% ethyl acetate in hexane as eluent, affording compound 1a (199 mg, 63 mmol 83%).

3.6. General Procedure for the Synthesis of (1-(2,4-Dioxo-1,2,3,4-Tetrahydroquinolin-3-yl)-1H-1,2,3-Triazol-4-yl)Methyl Acetates 1e,f (Scheme 2)

Acetic anhydride (12 mL, 12.9 g, 126 mmol) was added to a light yellow solution of compound 1c or 1d (6 mmol) in n class="Chemical">pyridine (18 mL) under stirring during 2 min. The reaction mixture was stirred for 1 h, followed by evaporation of volatiles under reduced pressure. The remaining pyridine was removed by co-distillation with ethanol (6 × 40 mL). The residue was triturated with water (300 mL) to form a white precipitate which was collected by filtration on a sintered glass filter with suction, washed with water to neutral and dried to give acetates 1e or 1f. The crude product was recrystallized from the solvent indicated below.

(1-(3-Methyl-2,4-dioxo-1,2,3,4-tetrahydroquinolin-3-yl)-1 Compound 1e (1.58 g, 5.04 mmol, 84%) was prepared from 1c (1.63 g, 6.0 mmol). Pale yellow solid, m.p. 145–148 °C (n class="Chemical">ethyl acetate); Rf = 0.33 (5% ethanol in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.06 (s, 3H, COCH3), 2.09 (s, 3H, C-3–CH3), 5.16 (s, 2H, CH2), 7.19–7.26 (m, 2H, H-6, H-8), 7.70–7.77 (m, 1H, H-7), 7.83 (dd, 1H, J = 8.0, 1.4 Hz, H-5), 8.45 (s, 1H, H-5A), 11.40 (s, 1H, H-1); 13C NMR (126 MHz, DMSO-d6) δ 20.6 (COCH3), 23.2 (C-3–CH3), 57.1 (CH2), 72.4 (C-3), 116.9 (C-8), 117.5 (C-4a), 123.3 (C-6), 125.8 (C-5A), 127.6 (C-5), 137.1 (C-7), 141.4 (C-4A), 141.6 (C-8a), 168.6 (C-2), 170.1 (COCH3), 190.7 (C-4); 15N NMR (51 MHz, DMSO-d6) δ 133.5 (N-1), 248.7 (N-1A), 354.1 (N-3A), 362.9 (N-2A); IR (cm−1): ν 3467, 3249, 3148, 2920, 1722, 1685, 1613, 1485, 1439, 1384, 1355, 1239, 1028, 759, 666; MS (EI) m/z (%): 315 (2, [M + 1]+), 314 (11, [M]+), 244 (22), 201 (22), 175 (71), 174 (31), 146 (43), 128 (26), 120 (25), 119 (27), 92 (24), 55 (20), 43 (100), 42 (26); HRMS (ESI+): m/z calcd for C15H15N4O4+ [M + H]+ 315.1088, found 315.1087. Anal. Calcd for C15H14N4O4 (314.30): C, 57.32; H, 4.49; N, 17.83%. Found: C, 57.32; H, 4.59; N, 17.58%.

(1-(2,4-Dioxo-3-phenyl-1,2,3,4-tetrahydroquinolin-3-yl)-1 Compound 1f (1.92 g, 5.1 mmol, 85%) was prepared from 1d (2.01 g, 6.0 mmol). Colorless crystals, m.p. 130–134 °C (n class="Chemical">ethanol, 80% yield of recrystallization); Rf = 0.40 (5% ethanol in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.04 (s, 3H, CH3), 5.13 (s, 2H, CH2), 7.09 (d, 1H, J = 8.1 Hz, H-8), 7.13–7.18 (m, 1H, H-6), 7.35–7.42 (m, 2H, H-2C, H-6C), 7.46–7.54 (m, 3H, H-3C, H-4C, H-5C), 7.59–7.65 (m, 1H, H-7), 7.83 (dd, 1H, J = 7.8, 1.3 Hz), 8.07 (s, 1H, H-5A), 11.62 (s, 1H, H-1); 13C NMR (126 MHz, DMSO-d6) δ 20.7 (CH3), 57.1 (CH2), 79.9 (C-3), 116.7 (C-8), 119.3 (C-4a), 123.4 (C-6), 127.0 (C-5A), 127.5 (C-5), 128.8 (C-2C, C-6C), 129.6 (C-3C, C-5C), 130.0 (C-1C), 130.6 (C-4C), 136.9 (C-7), 140.5 (C-8a), 140.8 (C-4A), 166.8 (C-2), 170.1 (COCH3), 188.8 (C-4); IR (cm–1): ν 3501, 3155, 2920, 1722, 1707, 1686, 1614, 1594, 1484, 1358, 1252, 1229, 1063, 857, 759; MS (EI) m/z (%): 377 (1, [M + 1]+), 376 (6, [M]+), 306 (16), 289 (18), 288 (54), 263 (15), 237 (50), 236 (100), 218 (34), 180 (14), 141 (14), 120 (24), 92 (14), 77 (19), 43 (16); HRMS (ESI+): m/z calcd for C20H17N4O4+ [M + H]+ 377.1244, found 377.1241.

3.7. General Procedure for the Synthesis of 3-(1H-1,2,3-Triazol-1-yl)-1-(prop-2-yn-1-yl)Quinoline-2,4(1H,3H)-Diones 7 (Table 3)

The mixture of the appropriate compound 1a,b,e,f (8.00 mmol), potassium carbonate (3.32 g, 24 mmol), and n class="Chemical">DMF (40 mL) was stirred for 40 min. During this time, the original yellow color of the suspension changed to orange. Afterwards, under continued stirring, an 80% solution of propargyl bromide (6c) in toluene (1.78 g, 12 mmol) diluted with DMF (20 mL) was added dropwise during 1 min and stirring was continued for 90 min. Then the mixture was reduced in vacuo and then toluene (50 mL) was added and the whole evaporated in vacuo at 50 °C. This was repeated seven times in order to remove traces of DMF. The residual light brown solid was suspended in chloroform (100 mL) and the suspension was acidified with 0.5 m HCl, whereas carbon dioxide was evolved owing to decomposition of unreacted potassium carbonate. The formed emulsion was diluted with water, organic phase was separated and aqueous phase was extracted with chloroform (5 × 40 mL). The organic phases were combined, dried (Na2SO4), filtered and taken down in vacuo. The residual solid TLC pure product was crystallized from a suitable solvent. The yields of prepared compounds 7 are given in Table 3.

3-Methyl-3-(4-n class="Chemical">phenyl-1 Colorless crystals, m.p. 187–189 °C (benzene); Rf = 0.63 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.16 (s, 3H, CH3), 3.39 (dd, 1H, J = 2.3, 2.3 Hz, C≡CH), 4.90 (dd, 1H, J = 18.1, 2.3 Hz, N-1–CHα), 4.97 (dd, 1H, J = 18.1, 2.3 Hz, N-1–CHβ), 7.34–7.42 (m, 2H, H-6, H-4B), 7.48 (dd, 2H, J = 7.7, 7.7 Hz, H-3B, H-5B), 7.61 (d, 1H, J = 8.4 Hz, H-8), 7.84–7.89 (m, 2H, H-2B, H-6B), 7.89–7.95 (m, 1H, H-7), 8.00 (dd, J = 7.7, 1.5 Hz, H-5), 8.89 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 23.3 (CH3), 32.7 (N-1–CH2), 72.6 (C-3), 75.4 (C≡CH), 78.2 (C≡CH), 116.7 (C-8), 119.0 (C-4a), 122.5 (C-5A), 124.2 (C-6), 125.1 (C-2B, C-6B), 128.1 (C-4B), 128.2 (C-5), 129.0 (C-3B, C-5B), 130.5 (C-1B), 137.3 (C-7), 140.8 (C-8a), 145.9 (C-4A), 167.7 (C-2), 189.7 (C-4); IR (cm−1): ν 3261, 3173, 2122, 1713, 1678, 1601, 1469, 1427, 1381, 1368, 1353, 1306, 1189, 769, 754; MS (EI) m/z (%): 357 (2, [M + 1]+), 356 (8, [M]+), 259 (10), 128 (11), 117 (16), 116 (100), 102 (17), 90 (11), 89 (16), 77 (10), 76 (10); HRMS (ESI+): m/z calcd for C21H17N4O2+ [M + H]+ 357.1346, found 357.1342. Anal. Calcd for C21H16N4O2 (356.38): C, 70.77; H, 4.53; N, 15.72%. Found: C, 70.81; H, 4.58; N, 15.82%.

3-Phenyl-3-(4-n class="Chemical">phenyl-1 Colorless crystals, m.p. 232–234 °C (ethanol); Rf = 0.69 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3) δ 2.34 (dd, 1H, J = 2.4, 2.4 Hz), 4.51 (dd, 1H, J = 17.8, 2.3 Hz), 5.37 (dd, 1H, J = 17.8, 2.3 Hz), 7.23 (dd, 1H, J = 7.6, 7.6 Hz), 7.26 (s, 1H), 7.27–7.31 (m, 1H), 7.32–7.40 (m, 3H), 7.43–7.51 (m, 3H), 7.51–7.56 (m, 2H), 7.62–7.69 (m, 1H), 7.73–7.81 (m, 2H), 8.05 (dd, 1H, J = 7.7, 1.4 Hz); 13C NMR (126 MHz, CDCl3) δ 33.6, 73.6, 76.9, 79.6, 115.8, 121.0, 122.3, 124.6, 126.0, 128.1, 128.8, 129.0, 129.2, 130.0, 130.1, 130.7, 131.3, 136.9, 140.6, 146.0, 165.8, 187.5; IR (cm−1): ν 3197, 2983, 2118, 1716, 1680, 1603, 1468, 1448, 1304, 1039, 870, 760, 752, 694; MS (EI) m/z (%): 419 (13, [M + 1]+), 418 (75, [M]+), 390 (43), 287 (22), 286 (31), 285 (89), 276 (25), 275 (100), 274 (28), 259 (70), 248 (46), 235 (53), 145 (52), 116 (95), 44 (99); HRMS (ESI+): m/z calcd for C26H19N4O2+ [M + H]+ 419.1503, found 419.1502. Anal. Calcd for C26H18N4O2: C, 74.63; H, 4.34; N, 13.39%. Found: C, 74.45; H, 4.40; N, 13.43%.

(1-(3-Methyl-2,4-dioxo-1-(prop-2-yn-1-yl)-1,2,3,4-tetrahydroquinolin-3-yl)-1 Colorless crystals, m.p. 159–161 °C (n class="Chemical">ethyl acetate); Rf = 0.29 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.06 (s, 3H, COCH3), 2.10 (s, 3H, C-3–CH3), 3.37 (dd, 1H, J = 2.4, 2.4 Hz, C≡CH), 4.84 (dd, 1H, J = 18.1, 2.4 Hz, N-1–CHα), 4.95 (dd, 1H, J = 18.1, 2.4 Hz, N-1–CHβ), 5.17 (s, 2H, OCH2), 7.37 (dd, 1H, J = 7.5, 7.5 Hz, H-6), 7.58 (d, 1H, J = 8.4 Hz, H-8), 7.87–7.93 (m, 1H, H-7), 7.96 (dd, 1H, J = 7.7, 1.5 Hz, H-5), 8.46 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 20.6 (COCH3), 23.4 (C-3–CH3), 32.6 (N-1–CH2), 57.1 (OCH2), 72.8 (C-3), 75.3 (C≡CH), 78.2 (C≡CH), 116.6 (C-8), 119.2 (C-4a), 124.0 (C-6), 126.0 (C-5A), 128.0 (C-5), 137.1 (C-7), 140.7 (C-8a), 141.5 (C-4A), 167.8 (C-2), 170.1 (COCH3), 189.63 (C-4); 15N NMR (51 MHz, DMSO-d6) δ 134.4 (N1), 247.9 (N-1A), 354.0 (N-3A), 363.4 (N-2A); IR (cm−1): ν 3256, 3152, 2122, 1721, 1687, 1604, 1471, 1383, 1306, 1246, 1194, 1053, 1008, 756; MS (EI) m/z (%): 353 (3, [M + 1]+), 352 (12, [M]+), 213 (69), 212 (34), 184 (19), 156 (32), 146 (17), 130 (19), 129 (21), 128 (22), 77 (17), 57 (16), 55 (23), 43 (100), 42 (17); HRMS (ESI+): m/z calcd for C18H17N4O4+ ([M+H]+): 353.1244, found 353.1246. Anal. Calcd for C18H16N4O4 (352.34): C, 61.36; H, 4.58; N, 15.90%. Found: C, 61.27; H, 4.64; N, 15.87%.

(1-(2,4-Dioxo-3-phenyl-1-(prop-2-yn-1-yl)-1,2,3,4-tetrahydroquinolin-3-yl)-1 Colorless crystals, m.p. 210–214 °C; Rf = 0.66 (5% n class="Chemical">ethanol in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.05 (s, 3H, COCH3), 3.41 (dd, 1H, J = 2.4, 2.3 Hz, C≡CH), 4.80 (dd, 1H, J = 18.0, 2.3 Hz, N-1–CHα), 5.09–5.20 (m, 3H, N-1–CHβ, OCH2), 7.24–7.32 (m, 3H, H-6, H-2C, H-6C), 7.41–7.51 (m, 4H, H-8, H-3C, H-4C, H-5C), 7.73–7.79 (m, 1H, H-7), 7.92 (dd, 1H, J = 7.7, 1.5 Hz, H-5), 8.15 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 20.6 (COCH3), 33.1 (N-1–CH2), 57.1 (OCH2), 75.5 (C≡CH), 77.9 (C≡CH), 80.0 (C-3), 116.3 (C-8), 120.9 (C-4a), 124.2 (C-6), 127.1 (C-5A), 127.8 (C-5), 128.6 (C-2C, C-6C), 129.5 (C-3C, C-5C), 129.9 (C-1C), 130.7 (C-4C), 136.7 (C-7), 140.0 (C-8a), 140.9 (C-4A), 165.8 (C-2), 170.1 (COCH3), 187.7 (C-4); IR (cm−1): ν 3227, 3152, 2116, 1736, 1715, 1683, 1602, 1467, 1379, 1303, 1251, 1036, 764, 747, 694; MS (EI) m/z (%): 415 (2, [M + 1]+), 414 (7, [M]+), 313 (26), 275 (72), 274 (63), 246 (28), 235 (31), 218 (29), 217 (30), 156 (26), 130 (29), 105 (22), 104 (29), 103 (22), 43 (100); HRMS (ESI+): m/z calcd for C23H19N4O4+ [M + H]+ 415.1401, found 415.1403. Anal. Calcd for C23H18N4O4: C, 66.66; H, 4.38; N, 13.52%. Found: C, 66.45; H, 4.39; N, 13.35%.

3.8. General Procedure for the Synthesis of Bis-Triazoles 2a,b,d,e,g,h,j,k by Employing CuSO4/Cu0/DMF Conditions (Table 4, Entries 1, 2, 4, 8, 10, 11, 13 and 14)

A solution of azidobenzene (8b, 197 mg, 1.65 mmol) or n class="Chemical">(azidomethyl)benzene (8a, 220 mg, 1.65 mmol) in DMF (4 mL) was added to a vigorously stirred mixture of the appropriate N‑propargylquinoline-2,4(1H,3H)-dione 7 (1.5 mmol), CuSO4∙5H2O (38 mg, 0.15 mmol) and granular copper (191 mg, 3.05 mmol) in DMF (5 mL). The reaction mixture was stirred in darkness at room temperature for the time given in Table 4. The color of the mixture became brown-black. Then, (NH4)2CO3 (432 mg, 4.5 mmol) and water (2 mL) were added to the reaction mixture and the stirring was continued for 10 min. The reaction mixture was poured into a narrow (1 cm in diameter) column of silica gel (15 g). The organic portion was eluted with 10% ethanol in chloroform (approximately 150 mL). The yellow eluate was washed with saturated aqueous NH4Cl (50 mL), dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation in vacuo. The TLC pure product thus prepared, with the exception of compounds 2d,e,k, was crystallized from suitable solvent. The yields of prepared compounds 2 are given in Table 4.

1-((1-Benzyl-1 Colorless crystals, m.p. 202–204 °C (n class="Chemical">ethanol); Rf = 0.40 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.18 (s, 3H, CH3), 5.24 (d, 1H, J = 16.2 Hz, N-1–CHα), 5.49 (d, 1H, J = 16.2 Hz, N-1–CHβ), 5.58 (s, 2H, N-1D–CH2), 7.24–7.29 (m, 2H, H-2E, H-6E), 7.29–7.40 (m, 5H, H-6, H-4B, H-3E, H-4E, H-5E), 7.49 (dd, 2H, J = 7.7, 7.7 Hz, H-3B, H-5B), 7.67 (d, 1H, J = 8.5 Hz, H-8), 7.79–7.90 (m, 3H, H-7, H-2B, H-6B), 7.96 (dd, 1H, J = 7.7, 1.4 Hz, H-5), 8.16 (s, 1H, H-5D), 8.87 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 23.4 (CH3), 38.7 (N-1–CH2), 52.8 (N-1D–CH2), 72.8 (C-3), 116.7 (C-8), 119.1 (C-4a), 122.5 (C-5A), 123.8 (C-5D), 123.9 (C-6), 125.1 (C-2B, C-6B), 127.9 (C-2E, C-6E), 128.0 (C-4B), 128.1 (C-5), 128.1 (C-4E), 128.7 (C-3E, C-5E), 129.1 (C-3B, C-5B), 130.6 (C-1B), 136.0 (C-1E), 137.2 (C-7), 141.5 (C-8a), 142.2 (C-4D), 145.9 (C-4A), 168.2 (C-2), 190.0 (C-4); IR (cm−1): ν 3137, 3128, 1711, 1673, 1600, 1471, 1387, 1051, 768, 761, 718, 694; MS (EI) m/z (%): 490 (2, [M + 1]+), 489 (6, [M]+), 289 (13), 145 (17), 144 (16), 117 (11), 116 (44), 91 (100), 90 (10), 89 (12); HRMS (ESI+): m/z calcd for C28H24N7O2+ [M + H]+ 490.1986, found 490.1981. Anal. Calcd for C28H23N7O2 (489.53) C, 68.70; H, 4.74; N, 20.03. Found: C, 68.71; H, 4.78; N, 20.36.

3-Methyl-3-(4-n class="Chemical">phenyl-1 Colorless crystals, m.p. 194–197 °C (benzene); Rf = 0.48 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.23 (s, 3H, CH3), 5.33 (d, 1H, J = 16.4 Hz, N-1–CHα), 5.62 (d, 1H, J = 16.4 Hz, N-1–CHβ), 7.31–7.39 (m, 2H, H-6, H-4B), 7.45–7.52 (m, 3H, H-3B, H-5B, H-4E), 7.55–7.62 (m, 2H, H-3E, H-5E), 7.70 (d, 1H, J = 8.5 Hz, H-8), 7.82–7.91 (m, 5H, H-7, H‑2B, H-6B, H-2E, H-6E), 7.98 (dd, 1H, J = 7.7, 1.5 Hz, H-5), 8.75 (s, 1H, H-5D), 8.87 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 23.4 (CH3), 38.7 (N-1–CH2), 73.0 (C-3), 116.8 (C-8), 119.2 (C-4a), 120.2 (C-2E, C-6E), 121.8 (C-5D), 122.5 (C-5A), 124.0 (C-6), 125.2 (C-2B, C-6B), 128.1 (C-4B), 128.1 (C-5), 128.8 (C-4E), 129.1 (C-3B, C-5B), 129.9 (C-3E, C-5E), 130.6 (C-1B), 136.5 (C-1E), 137.3 (C-7), 141.6 (C-8a), 143.3 (C-4D), 146.0 (C-4A), 168.3 (C-2), 190.0 (C-4); 15N NMR (51 MHz, DMSO-d6) δ 136.3 (N1), 248.9 (N-1A), 255.7 (N-D-1), 347.1 (N-3A), 353.4 (N-3D), 358.1 (N-2D), 363.2 (N-2A); IR (cm−1): ν 3275, 1721, 1690, 1613, 1485, 1353, 854, 771, 756, 698, 666, 607, 520; MS (EI) m/z (%): 476 (3, [M + 1]+), 475 (8, [M]+), 289 (14), 145 (12), 131 (11), 130 (100), 129 (18), 128 (11), 116 (56), 104 (12), 103 (16), 102 (12), 89 (12), 77 (69); HRMS (ESI+): m/z calcd for C27H22N7O2+ [M + H]+ 476.1829, found 476.1825. Anal. Calcd for C27H21N7O2 (475.50): C, 68.20; H, 4.45; N, 20.62%. Found: C, 68.48; H, 4.53; N, 20.60%.

(1-(1-((1-Benzyl-1 Colorless powder, m.p. 69–82 °C; Rf = 0.42 (30% n class="Chemical">ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3), δ 2.09 (s, 3H, COCH3), 2.12 (s, 3H, C-3–CH3), 5.25 (s, 2H, OCH2), 5.33 (s, 2H, N-1-CH2), 5.45 (d, 1H, J = 14.8 Hz, N-1D–CHα), 5.51 (d, 1H, J = 14.8 Hz, N-1D–CHβ), 7.23–7.26 (m, 3H, H-6, H-2E, H-6E), 7.32–7.38 (m, 3H, H-3E, H-4E, H-5E), 7.55 (s, 1H, H-5D), 7.73 (ddd, 1H, J = 8.7, 7.1, 1.6 Hz, H-7), 7.78 (s, 1H, H-5A), 7.82 (d, 1H, J = 8.4 Hz, H-8), 8.02 (dd, 1H, J = 7.7, 1.6 Hz, H-5); 13C NMR (126 MHz, CDCl3) δ 21.1 (COCH3), 23.5 (C-3–CH3), 39.5 (N-1–CH2), 54.5 (N-1D–CH2), 57.7 (OCH2), 71.6 (C-3), 116.9 (C-8), 119.2 (C-4a), 123.5 (C-5D), 124.2 (C-5A), 124.6 (C-6), 128.3 (C-2E, C-6E), 129.0 (C-4E), 129.3 (C-3E, C-5E), 129.3 (C-5), 134.4 (C-1E), 137.8 (C-7), 141.7 (C-8a), 142.3 (C-4A), 142.9 (C-4D), 168.2 (C-2), 171.1 (COCH3), 189.4 (C-4); 15N NMR (51 MHz, CDCl3) δ 138.7 (N-1), 248.4 (N-1A), 250.4 (N-1D), 350.0 (N-3D), 355.2 (N-3A), 361.6 (N-2A), 362.6 (N-2D); IR (cm−1): ν 3143, 2930, 1739, 1717, 1679, 1602, 1470, 1384, 1243, 1186, 1050, 1028, 765, 721, 664; MS (EI) m/z (%): 486 (0.3, [M + 1]+), 485 (1, [M]+), 144 (18), 91 (100), 43 (24); HRMS (ESI+): m/z calcd for C25H24N7O4+ [M + H]+ 486.1884, found 486.1884.

(1-(3-Methyl-2,4-dioxo-1-((1-n class="Chemical">phenyl-1 Colorless powder, m.p. 78–97 °C; Rf = 0.25 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3) δ 2.10 (s, 3H, COCH3), 2.20 (s, 3H, C-3–CH3), 5.27 (s, 2H, OCH2), 5.42 (d, 1H, J = 15.8 Hz, N-1–CHα), 5.52 (d, 1H, J = 15.8 Hz, N-1–CHβ), 7.27–7.30 (m, 1H, H-6), 7.41–7.47 (m, 1H, H-4E), 7.49–7.55 (m, 2H, H-3E, H-5E), 7.69–7.74 (m, 2H, H-2E, H-6E), 7.76 (ddd, 1H, J = 8.1, 7.7, 1.6 Hz, H-7), 7.85 (d, 1H, J = 7.3 Hz, H-8), 7.86 (s, 1H, H-5A), 8.05 (dd, 1H, J = 7.8, 1.5 Hz, H-5), 8.10 (s, 1H, H-5D); 13C NMR (126 MHz, CDCl3) δ 21.0 (COCH3), 23.4 (C-3–CH3), 39.5 (N-1-CH2), 57.7 (OCH2), 71.5 (C-3), 116.8 (C-8), 119.2 (C-4a), 120.6 (C-2E, C-6E), 121.7 (C-5D), 124.1 (C-5A), 124.7 (C-6), 129.1 (C-4E), 129.4 (C-5), 129.9 (C-3E, C-5E), 136.9 (C-1E), 137.8 (C-7), 141.7 (C-8a), 142.3 (C-4A), 143.2 (C-4D), 168.3 (C-2), 171.1 (COCH3), 189.4 (C-4); 15N NMR (51 MHz, CDCl3) δ 138.7 (N-1), 248.8 (N-1A), 256.3 (N-1D), 351.9 (N-3D), 355.5 (N-3A); IR (cm−1): ν 3145, 2926, 1740, 1717, 1681, 1601, 1470, 1384, 1242, 1184, 1046, 761, 691, 664; MS (EI) m/z (%): 472 (0.9, [M + 1]+), 471 (3, [M]+), 303 (20), 302 (17), 131 (13), 130 (100), 129 (14), 77 (44), 43 (25); HRMS (ESI+): m/z calcd for C24H22N7O4+ [M + H]+ 472.1728, found 472.1726.

1-((1-Benzyl-1 Colorless crystals, m.p. 142–145 °C (n class="Chemical">ethanol); Rf = 0.42 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 5.15 (d, 1H, J = 15.8 Hz, N-1–CHα), 5.62 (s, 2H, N-1D–CH2), 5.63 (d, 1H, J = 15.8 Hz, N-1–CHβ), 7.22–7.50 (m, 14H, H-6, H-3B, H-4B, H-5B, H-2C, H-3C, H-4C, H-5C, H-6C, H-2E, H-3E, H-4E, H-5E, H-6E), 7.68 (d, 1H, J = 7.8 Hz, H-8), 7.73 (ddd, 1H, J = 8.5, 7.1, 1.7 Hz, H-7), 7.80–7.83 (m, 2H, H-2B, H-6B), 7.92 (dd, 1H, J = 7.7, 1.5 Hz, H-5), 8.24 (s, 1H, H-5D), 8.51 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 39.2 (N-1–CH2), 52.8 (N-1D–CH2), 80.1 (C-3), 116.7 (C-8), 120.9 (C-4a), 123.4 (C-5A), 124.0 (C-6), 124.2 (C-5D), 125.2 (C-2B, C-6B), 127.9 (C-5), 128.0 (C-4C, C-2E, C-6E), 128.2 (C-4B),128.7 (C-1C), 128.8 (C-3E, C-5E), 129.0 (C-3B, C-5B), 129.4 (C-2C, C-6C), 129.8 (C-1B), 130.5 (C-3C, C-5C, C-4E), 136.0 (C-1E), 136.8 (C-7), 140.8 (C-8a), 141.9 (C-4D), 145.4 (C-4A), 166.2 (C-2), 188.2 (C-4); IR (cm−1): ν 3434, 3138, 3062, 1716, 1678, 1601, 1468, 1375, 1307, 1035, 870, 761, 724, 695; MS (EI) m/z (%): 552 (1, [M + 1]+), 551 (3, [M]+), 289 (23), 236 (11), 145 (18), 144 (17), 116 (31), 104 (10), 91 (100), 89 (11), 77 (16); HRMS (ESI+): m/z calcd for C33H26N7O2+ [M + H]+ 552.2142, found 552.2133. Anal. Calcd for C33H25N7O2 (551.60): C, 71.86; H, 4.57; N, 17.78%. Found: C, 71.58; H, 4.58; N, 17.73%.

3-Phenyl-3-(4-n class="Chemical">phenyl-1 Colorless crystals, m.p. 152–157 °C (ethanol); Rf = 0.54 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 5.33 (d, 1H, J = 16.1 Hz, N-1–CHα), 5.71 (d, 1H, J = 16.1 Hz, N-1–CHβ), 7.25–7.29 (m, 1H, H-6), 7.32–7.48 (m, 8H, H-3B, H-4B, H-5B, H-2C, H-3C, H-4C, H-5C, H-6C), 7.48–7.53 (m, 1H, H-4E), 7.58–7.64 (m, 2H, H-3E, H-5E), 7.70 (d, 1H, J = 8.2 Hz, H-8), 7.72–7.77 (m, 1H, H-7), 7.81–7.85 (m, 2H, H-2B, H-6B), 7.88–7.93 (m, 2H, H-2E, H-6E), 7.95 (dd, 1H, J = 7.7, 1.5 Hz, H-5), 8.54 (s, 1H, H-5A), 8.83 (s, 1H, H-5D); 13C NMR (126 MHz, DMSO-d6) δ 39.0 (N-1–CH2), 80.3 (C-3), 116.7 (C-8), 120.2 (C-2E, C-6E), 120.9 (C-4a), 122.3 (C-5D), 123.5 (C-5A), 124.1 (C-6), 125.2 (C-2B, C-6B), 127.9 (C-5), 128.0 (C-4B), 128.9 (C-4E), 128.9 (C-2C, C-6C), 129.0 (C-3B, C-3B), 129.4 (C-3C, C-5C), 129.9 (C-1C), 130.0 (C-3E, C-5E), 130.5 (C-4C), 130.6 (C-1B), 136.5 (C-1E), 136.8 (C-7), 140.7 (C-8a), 142.9 (C-4D), 145.4 (C-4A), 166.4 (C-2), 188.2 (C-4); IR (cm−1): ν 3447, 3142, 3060, 1716, 1679, 1600, 1468, 1449, 1375, 1305, 1040, 871, 758, 693; MS (EI) m/z (%): 538 (1, [M + 1]+), 537 (3, [M]+), 366 (14), 262 (10), 236 (17), 145 (29), 131 (10), 130 (100), 129 (19), 128 (11), 118 (10), 116 (38), 104 (14), 103 (17), 102 (13), 90 (12), 89 (15), 77 (71), 51 (12); HRMS (ESI+): m/z calcd for C32H24N7O2+ ([M+H]+) 538.1986, found 538.1976. Anal. Calcd for Anal. calcd for C32H23N7O2 (537.57) C, 71.50; H, 4.31; N, 18.24%. Found: C, 71.22; H, 4.32; N, 17.94%.

(1-(1-((1-Benzyl-1 Colorless powder, m.p. 188–194 °C (n class="Chemical">ethanol); Rf = 0.41 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3) δ 2.04 (s, 3H, CH3), 5.17 (s, 2H, OCH2), 5.21 (d, 1H, J = 15.6 Hz, N-1–CHα), 5.43 (d, 1H, J = 14.8 Hz, N-1D–CHα), 5.51 (d, 1H, J = 15.6 Hz, N-1–CHβ), 5.55 (d, 1H, J = 14.8 Hz, N-1D–CHβ), 7.08 (s, 1H, H-5A), 7.18 (ddd, 1H, J = 7.5, 7.5, 0.8 Hz, H-6), 7.23–7.29 (m, 4H, H-3C, H-5C, H-2E, H-6E), 7.29–7.33 (m, 2H, H-2C, H-6C), 7.34–7.39 (m, 3H, H-3E, H-4E, H-5E), 7.38–7.44 (m, 1H, H-4C), 7.58 (s, 1H, H-5D), 7.63 (ddd, 1H, J = 8.4, 7.4, 1.7 Hz, H-7), 7.75 (d, 1H, J = 8.3 Hz, H-8), 7.99 (dd, 1H, J = 7.7, 1.7 Hz, H-5); 13C NMR (126 MHz, CDCl3) δ 21.0 (CH3), 39.9 (N-1–CH2), 54.5 (N-1D–CH2), 57.6 (OCH2), 79.6 (C-3), 116.8 (C-8), 120.9 (C-4a), 123.5 (C-5D), 124.6 (C-6), 126.4 (C-5A), 128.3 (C-2E, C-6E), 128.7 (C-2C, C-6C), 129.0 (C-5), 129.1 (C-4E), 129.4 (C-3E, C-5E), 129.7 (C-1C), 130.0 (C-3C, C-5C), 131.3 (C-4C), 134.5 (C-1E), 137.2 (C-7), 140.9 (C-4A), 141.1 (C-8a), 142.9 (C-4D), 166.6 (C-2), 171.0 (COCH3), 187.9 (C-4); 15N NMR (51 MHz, CDCl3) δ 140.4 (N-1), 249.8 (N-1A), 250.4 (N-1D), 350.5 (N-3D), 356.9 (N-3A), 362.9 (N-2D), 365.1 (N-2A); IR (cm−1): ν 3142, 2927, 1740, 1717, 1679, 1602, 1469, 1377, 1244, 768, 749, 714, 697; MS (EI) m/z (%): 548 (0.1, [M + 1]+), 547 (0.3, [M]+), 347 (13), 289 (13), 144 (14), 105 (10), 104 (13), 91 (100), 43 (29); HRMS (ESI+): m/z calcd for C30H26N7O4+ [M + H]+ 548.2041, found 548.2032.

(1-(2,4-Dioxo-3-phenyl-1-((1-n class="Chemical">phenyl-1 Colorless powder, m.p. 93–105 °C; Rf = 0.42 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3) δ 2.05 (s, 3H, CH3), 5.19 (s, 2H, OCH2), 5.42 (d, 1H, J = 15.7 Hz, N-1–CHα), 5.55 (d, 1H, J = 15.7 Hz, N-1–CHβ), 7.14 (s, 1H, H-5A), 7.20 (ddd, 1H, J = 7.6, 7.6, 0.8 Hz, H-6), 7.38–7.49 (m, 6H, H-2C, H-3C, H-4C, H-5C, H-6C, H-4E), 7.49–7.55 (m, 2H, H-3E, H-5E), 7.66 (ddd, 1H, J = 8.5, 7.3, 1.7 Hz, H-7), 7.68–7.72 (m, 2H, H-2E, H-6E), 7.76 (d, 1H, J = 8.4 Hz, H-8), 8.03 (dd, 1H, J = 7.8, 1.5 Hz, H-5), 8.05 (s, 1H, H-5D); 13C NMR (126 MHz, CDCl3) δ 21.0 (CH3), 39.8 (N-1-CH2), 57.6 (OCH2), 79.6 (C-3), 116.7 (C-8), 120.7 (C-2E, C-6E), 120.9 (C-4a), 121.8 (C-5D), 124.7 (C-6), 126.4 (C-5A), 128.9 (C-2C, C-6C), 129.1 (C-5), 129.2 (C-4E), 129.9 (C-1C), 130.0 (C-3E, C-5E), 130.2 (C-3C, C-5C), 131.4 (C-4C), 136.9 (C-1E), 137.4 (C-7), 140.9 (C-4A), 140.9 (C-8a), 143.2 (C-4D), 166.9 (C-2), 171.0 (COCH3), 187.9 (C-4); 15N NMR (51 MHz, CDCl3) δ 140.4 (N-1), 249.9 (N-1A), 256.3 (N-1D), 352.9 (N-3D), 357.2 (N-3A); IR (cm−1): ν 3146, 2962, 1741, 1718, 1681, 1600, 1468, 1376, 1243, 1043, 762, 693, 665, 608; MS (EI) m/z (%): 534 (0.2, [M + 1]+), 533 (0.6, [M]+), 366 (12), 365 (11), 262 (12), 131 (11), 130 (100), 129 (19), 128 (12), 104 (14), 103 (16), 99 (18), 77 (62), 44 (17), 43 (52); HRMS (ESI+): m/z calcd for C29H24N7O4+ [M + H]+ 534.1884, found 534.1882.

3.9. General Procedure for the Synthesis of Bis-Triazoles 2c,f,i,l by Employing CuSO4/Cu0/DMF Conditions (Table 4, Entries 3, 9, 12 and 15)

A mixture of the appropriate N-propargyln class="Chemical">quinoline-2,4(1H,3H)-dione 7 (1.5 mmol), tetrazolo[1,5-a]pyridine (189 mg, 1.58 mmol), CuSO4∙5H2O (38 mg, 0.15 mmol), granular copper (191 mg, 3.05 mmol) and DMF (9 mL) was heated in darkness to 95–105 °C (oil bath) for the time given in Table 4, whereas the color of the mixture changed from brown-black to dark green. The mixture was then allowed to cool to room temperature. Subsequently, (NH4)2CO3 (432 mg, 4.5 mmol) and water (2 mL) were added and after stirring for 15 min, the mixture was poured into a narrow (1 cm diameter) column of silica gel (15 g). The organic portion was eluted from the column with 10% ethanol in chloroform. The yellow eluate was washed with saturated aqueous NH4Cl (50 mL), dried over anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation in vacuo. In the cases of 2c,i, the residue, which was TLC pure compound, was crystallized from suitable solvent. In the cases of 2f,l, the residue was purified by chromatography on silica gel column using chloroform as eluent. The yields of prepared compounds 2 are given in Table 4.

3-Methyl-3-(4-n class="Chemical">phenyl-1 Colorless crystals, m.p. 188–191 °C (benzene); Rf = 0.29 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.23 (s, 3H, CH3), 5.42 (d, 1H, J = 16.5 Hz, N-1–CHα), 5.58 (d, 1H, J = 16.5 Hz, N-1–CHβ), 7.28–7.40 (m, 2H, H-6, H-4B), 7.43–7.51 (m, 2H, H-3B, H-5B), 7.51–7.57 (m, 1H, H-5E), 7.64 (d, 1H, J = 8.4 Hz, H-8), 7.78–7.90 (m, 3H, H-7, H-2B, H-6B), 7.99 (d, 1H, J = 7.5 Hz, H-5), 8.07–8.17 (m, 2H, H-3E, H-4E), 8.54–8.61 (m, 1H, H-6E), 8.82 (s, 1H, H-5D), 8.87 (s, 1H, H-5A); 13C NMR (126 MHz, DMSO-d6) δ 23.4 (CH3), 38.7 (N-1–CH2), 73.0 (C-3), 113.7 (C-3E), 116.6 (C-8), 119.3 (C-4a), 120.6 (C-5D), 122.5 (C-5A), 123.9 (C-6), 124.5 (C-5E), 125.2 (C-2B, C-6B), 128.1 (C-4B), 128.1 (C-5), 129.1 (C-3B, C-5B), 130.5 (C-1B), 137.2 (C-7), 140.3 (C-4E), 141.4 (C-8a), 143.2 (C-4D), 146.0 (C-4A), 148.4 (C-2E), 149.0 (C-6E), 168.5 (C-2), 189.9 (C-4); 15N NMR (51 MHz, DMSO-d6) δ 135.8 (N-1), 248.9 (N-1A), 260.5 (N-1D), 284.9 (N-1E), 347.1 (N-3A), 356.9 (N-3D), 358.6 (N-2D), 363.4 (N-2A); IR (cm−1): ν 3426, 3126, 2972, 1706, 1674, 1601, 1471, 1378, 1310, 1232, 1041, 777, 764; MS (EI) m/z (%): 477 (2, [M + 1]+), 476 (7, [M]+), 289 (11), 145 (14), 132 (14), 131 (96), 116 (50), 102 (10), 90 (10), 89 (13), 79 (20), 78 (100), 77 (10), 51 (10); HRMS (ESI+): m/z calcd for C26H21N8O2+ [M + H]+ 477.1782, found 477.1773. Anal. Calcd for C26H20N8O2 (476.48) C, 65.54; H, 4.23; N, 23.52%. Found: C, 65.68; H, 4.21; N, 23.63%.

(1-(3-Methyl-2,4-dioxo-1-((1-(pyridin-2-yl)-1 Colorless powder, m.p. 69–82 °C; Rf = 0.29 (30% n class="Chemical">ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 2.06 (s, 3H, COCH3), 2.18 (s, 3H, C3–CH3), 5.17 (d, 1H, J = 12.7 Hz, O–CHα), 5.20 (d, 1H, J = 12.7 Hz, O–CHβ), 5.41 (d, 1H, J = 16.5 Hz, N-1–CHα), 5.53 (d, 1H, J = 16.5 Hz, N-1–CHβ), 7.31 (dd, 1H, J = 7.4, 7.4 Hz, H-6), 7.54 (dd, 1H, J = 8.8, 4.5 Hz, H-5E), 7.59 (d, 1H, J = 8.5 Hz, H-8), 7.77–7.83 (m, 1H, H-7), 7.96 (dd, 1H, J = 7.7 Hz, J = 1.6 Hz, H-5), 8.08–8.14 (m, 2H, H-3E, H-4E), 8.47 (s, 1H, H-5A), 8.55–8.59 (m, 1H, H-6E), 8.82 (s, 1H, H-5D); 13C NMR (126 MHz, DMSO-d6) δ 20.6 (COCH3), 23.5 (C3–CH3), 38.7 (N-1–CH2), 57.2 (OCH2), 73.3 (C-3), 113.7 (C-3E), 116.5 (C-8), 119.4 (C-4a), 120.6 (C-5D), 123.8 (C-6), 124.4 (C-5E), 126.1 (C-5A), 127.9 (C-5), 137.0 (C-7), 140.2 (C-4E), 141.3 (C-8a), 141.6 (C-4A), 143.2 (C-4D), 148.3 (C-2E), 148.9 (C-6E), 168.6 (C-2), 170.1 (COCH3), 189.9 (C-4); 15N NMR (51 MHz, DMSO-d6) δ 135.3 (N1), 247.6 (N-1A), 260.0 (N-1D), 284.7 (N-1E), 353.4 (N-3A), 356.5 (N-3D), 361.9 (N-2D), 363.7 (N-2A); IR (cm−1): ν 3152, 1741, 1718 1681, 1600, 1471, 1384, 1314, 1242, 1183, 1038, 782, 756, 663; MS (EI) m/z (%): 473 (0.7, [M + 1]+), 472 (2, [M]+), 304 (27), 303 (26), 302 (17), 132 (13), 131 (100), 79 (22), 78 (100), 43 (21); HRMS (ESI+): m/z calcd for C23H21N8O4+ [M + H]+ 473.1680, found 473.1684. Anal. Calcd for C23H20N8O4·½H2O (472.46): C, 57.38; H, 4.40; N, 23.27%. Found: C, 57.39; H, 4.36; N, 23.47%.

3-Phenyl-3-(4-n class="Chemical">phenyl-1 Colorless crystals, m.p. 188–192 °C (benzene); Rf = 0.50 (30% ethyl acetate in chloroform); 1H NMR (500 MHz, DMSO-d6) δ 5.44 (d, 1H, J = 16.3 Hz, N-1–CHα), 5.67 (d, 1H, J = 16.3 Hz, N-1–CHβ), 7.26 (dd, 1H, J = 7.5, 7.5 Hz, H-6), 7.32–7.40 (m, 3H, H-4B, H-2C, H-6C), 7.41–7.52 (m, 5H, H-3B, H-5B, H-3C, H-4C, H-5C), 7.52–7.61 (m, 2H, H-8, H-5E), 7.68–7.75 (m, 1H, H-7), 7.78–7.86 (m, 2H, H-2B, H-6B), 7.96 (dd, 1H, J = 7.7, 1.5 Hz, H-5), 8.09–8.16 (m, 2H, H-3E, H-4E), 8.58 (s, 1H, H-5A), 8.60 (ddd, 1H, J = 4.8, 1.3, 1.3 Hz, H-6E), 8.81 (s, 1H, H-5D); 13C NMR (126 MHz, DMSO-d6) δ 39.1 (N-1–CH2), 80.4 (C-3), 113.7 (C-3E), 116.5 (C-8), 120.8 (C-5D), 120.9 (C-4a), 123.4 (C-5A), 124.0 (C-6), 124.5 (C-5E), 125.2 (C-2B, C-6B), 127.9 (C-5), 128.0 (C-4B), 128.9 (C-2C, C-6C), 129.0 (C-3B, C-5B), 129.4 (C-3C, C-5C), 130.0 (C-1C), 130.5 (C-4C), 130.6 (C-1B), 136.8 (C-7), 140.2 (C-4E), 140.5 (C-8a), 143.0 (C-4D), 145.4 (C-4A), 148.3 (C-2E), 149.0 (C-6E), 166.6 (C-2), 188.1 (C-4); 15N NMR (51 MHz, DMSO-d6) δ 137.5 (N1), 248.7 (N-1A), 260.4 (N-1D), 284.8 (N-1E), 347.2 (N-3A), 357.7 (N-3D), 367.4 (N-2A); IR (cm−1): ν 3418, 2973, 1718, 1679, 1596, 1477, 1467, 1450, 1049, 1031, 773, 766, 757, 701; MS (EI) m/z (%): 539 (1, [M + 1]+), 538 (3, [M]+), 236 (11), 145 (16), 132 (14), 131 (100), 116 (32), 91 (11), 89 (11), 79 (15), 78 (85), 77 (13); HRMS (ESI+): m/z calcd for C31H23N8O2+ [M + H]+ 539.1938, found 539.1932. Anal. calcd for C31H22N8O2 (538.19): C, 69.13; H, 4.12; N, 20.81%. Found: C, 68.91; H, 4.17; N, 20.66%.

(1-(2,4-Dioxo-3-phenyl-1-((1-(pyridin-2-yl)-1 Colorless powder, m.p. 93–102 °C; Rf = 0.18 (30% n class="Chemical">ethyl acetate in chloroform); 1H NMR (500 MHz, CDCl3) δ 2.05 (s, 3H, COCH3), 5.19 (s, 2H, OCH2), 5.30 (d, 1H, J = 15.8 Hz, N-1–CHα), 5.71 (d, 1H, J = 15.8 Hz, N-1–CHβ), 7.13 (s, 1H, H-5A), 7.19 (dd, 1H, J = 7.5, 7.5 Hz, H-6), 7.36 (dd, 1H, J = 7.3, 4.9 Hz, H-5E), 7.38–7.42 (m, 2H, H-3C, H-5C), 7.42–7.48 (m, 3H, H-2C, H-4C, H-6C), 7.63 (ddd, 1H, J = 8.3, 7.4, 1.6 Hz, H-7), 7.70 (d, 1H, J = 8.4 Hz, H-8), 7.88–7.95 (m, 1H, H-4E), 8.02 (dd, 1H, J = 7.8, 1.5 Hz, H-5), 8.15 (d, 1H, J = 8.2 Hz, H-3E), 8.47–8.53 (m, 1H, H-6E), 8.63 (s, 1H, H-5D); 13C NMR (126 MHz, CDCl3) δ 21.0 (COCH3), 39.9 (N-1–CH2), 57.6 (OCH2), 79.7 (C-3), 113.9 (C-3E), 116.6 (C-8), 121.0 (C-4a), 121.0 (C-5D), 124.0 (C-5E), 124.6 (C-6), 126.4 (C-5A), 128.9 (C-2C, C-6C), 129.1 (C-5), 129.7 (C-1C), 130.2 (C-3C, C-5C), 131.3 (C-4C), 137.2 (C-7), 139.3 (C-4E), 140.9 (C-4A), 141.2 (C-8a), 143.0 (C-4D), 148.9 (C-6E), 149.0 (C-2E), 166.6 (C-2), 171.0 (COCH3), 187.9 (C-4); 15N NMR (51 MHz, CDCl3) δ 138.9 (N-1), 249.7 (N-1A), 261.2 (N-1D), 285.1 (N-1E), 355.8 (N-3D), 357.1 (N-3A); IR (cm−1): ν 3155, 2926, 1741, 1718, 1682, 1599, 1470, 1375, 1313, 1243, 1034, 779, 697, 665; MS (EI) m/z (%): 535 (0.4, [M + 1]+), 534 (0.7, [M]+), 132 (14), 131 (100), 79 (19), 78 (93), 44 (11), 43 (31); HRMS (ESI+): m/z calcd for C28H23N8O4+ [M + H]+ 535.1837, found 535.1846.

3.10. Synthesis of Bis-Triazole 2d by Employing CH2Cl2/Water/CuSO4∙5H2O/Na-Ascorbate Conditions (Table 4, Entry 5)

To a solution of acetylene 7c (132 mg, 0.375 mmol) and n class="Chemical">azide 8a (52.4 mg, 0.394 mmol) in dichloromethane (6.5 mL) a solution of sodium ascorbate (59.5 mg, 0.3 mmol) in water (5.5 mL), and a solution of CuSO4∙5H2O (7.5 mg, 0.03 mmol) in water (1 mL) were added. The two-phase liquid reaction mixture was stirred in darkness at room temperature until the compound 7c reacted completely according to TLC analysis (4 h). The reaction mixture was diluted with water (50 mL) and extracted with chloroform (4 × 30 mL). The combined organic layers were dried (Na2SO4), filtered, and evaporated to dryness. The residue was dissolved in chloroform (5 mL) and subjected to silica gel (25 g) column chromatography using 67% ethyl acetate in petroleum ether as eluent, affording product 2d (155 mg, 0.32 mmol, 85%).

3.11. Synthesis of Bis-Triazole 2d by Employing t-BuOH/Water/CH3CN/CuSO4∙5H2O/Na-Ascorbate Conditions (Table 4, Entry 6)

To a mixture of acetylene 7c (264 mg, 0.75 mmol), n class="Chemical">azide 8a (105 mg, 0.79 mmol) and t-BuOH (3.5 mL) a solution of Na-ascorbate (30 mg, 0.15 mmol) in water (2.5 mL), and a solution of CuSO4∙5H2O (4 mg, 0.02 mmol) in water (1 mL) were added. The reaction mixture was stirred in darkness at room temperature for 9 h. Then a solution of Na-ascorbate (89 mg, 0.45 mmol) in water (1 mL), and a solution of CuSO4∙5H2O (11 mg, 0.044 mmol) in water (1 mL) and t-BuOH (2 mL) were added. The reaction mixture was stirred for additional 20 h. The resulting sticky sediment that formed in the course of the reaction was dissolved by addition of acetonitrile (3 mL) to the reaction mixture. The reaction mixture was stirred for additional 19 h. Although the azide and acetylene coupling partners were still present in the reaction mixture, as judged by TLC analysis, the reaction was stopped by the addition of water (50 mL) and extracted with chloroform (4 × 30 mL). The combined organic layers were dried (Na2SO4), filtered, and evaporated to dryness. The residue was dissolved in chloroform and subjected to silica gel (35 g) column chromatography using 67% ethyl acetate in petroleum ether as eluent, affording regenerated starting acetylene 7c (48 mg, 0.14 mmol, 18%) and product 2d (295 mg, 0.61 mmol, 81%).

3.12. Synthesis of Bis-Triazole 2d by Employing t-BuOH/Water/CuSO4∙5H2O/l-Ascorbic Acid Conditions (Table 4, Entry 7)

To a mixture of acetylene 7c (264 mg, 0.75 mmol) and n class="Chemical">azide 8a (105 mg, 0.79 mmol) a solution of l-ascorbic acid (13 mg, 0.074 mmol) and CuSO4∙5H2O (2 mg, 0.008 mmol) in water (3.5 mL), and t-BuOH (3.5 mL) were added. The reaction mixture was stirred in darkness at room temperature. After 8.5 h and 22 h of stirring additional portions of l-ascorbic acid/CuSO4∙5H2O/water/t-BuOH (40 mg, 0.23 mmol/6 mg, 0.02 mmol/1 mL/1 mL and 53 mg, 0.3 mmol/7.5 mg, 0.03 mmol/1 mL/1 mL, respectively) were added. Although after stirring for additional 23 h (total reaction time 45 h), TLC analysis indicated the presence of azide and acetylene starting compounds, the heterogeneous reaction mixture (a sticky sediment was formed) was diluted with water and extracted with chloroform (5 × 50 mL). The combined organic layers were dried (Na2SO4), filtered, and evaporated to dryness. The residue was dissolved in chloroform (5 mL) and subjected to silica gel (35 g) column chromatography using 33% ethyl acetate in petroleum ether as eluent, affording regenerated starting acetylene 7c (114 mg, 0.32 mmol, 43%) and product 2d (165 mg, 0.34 mmol 45%).

3.13. 3-Azido-3-methyl-1-(prop-2-yn-1-yl)Quinoline-2,4(1H,3H)-Dione (9a) (Scheme 3)

A mixture of the azide 5a (649 mg, 3.0 mmol) and n class="Chemical">potassium carbonate (1.24 g, 9 mmol) in DMF (15 mL) was stirred at room temperature in darkness for 40 min. Propargyl bromide (6c, 80% solution in toluene, 669 mg, 4.5 mmol) diluted with DMF (7 mL) was added dropwise under stirring during 1 min. The reaction mixture was stirred for 6 h, during which time it turned yellow, diluted with cold water (200 mL) and extracted with chloroform (5 × 50 mL). The combined organic layers were dried (Na2SO4), filtered, and evaporated to dryness. Trace amounts of DMF were removed by five subsequent co-destilations in vacuo at 50 °C with toluene (30 mL). The residual yellow oil was dissolved in chloroform (5 mL) and chromatographed on column silica gel (35 g) using chloroform as eluent, affording product 9a (717 mg, 2.82 mmol, 94%, dried in vacuo to constant weight) as off-white oily material, that was pure by TLC (Rf = 0.57; chloroform); 1H NMR (500 MHz, CDCl3) δ 1.79 (s, 3H), 2.29 (dd, 1H, J = 2.5, 2.5 Hz), 4.67 (dd, 1H, J = 17.8, 2.5 Hz), 4.98 (dd, 1H, J = 17.8, 2.5 Hz), 7.26 (ddd, 1H, J = 7.7, 7.4, 0.8 Hz), 7.35 (d, 1H, J = 8.3 Hz), 7.71 (ddd, 1H, J = 8.3, 7.4, 1.7 Hz), 8.02 (dd, 1H, J = 7.7, 1.7 Hz); 13C NMR (126 MHz, CDCl3) δ 23.6, 32.7, 70.7, 73.4, 77.1, 115.8, 119.6, 124.4, 129.0, 136.9, 140.8, 169.1, 191.1; IR (cm−1): ν 3241, 2980, 2138, 2107, 1711, 1678, 1603, 1471, 1383, 1366, 1305, 1285, 1260, 1218, 762; HRMS (ESI+): m/z calcd for C13H11N4O2+ [M + H]+ 255.0877, found 255.0877; calcd for C13H11N2O2+ [M − N2 + H]+ 227.0815, found 227.0814.

3.14. Synthesis of Triazole from Phenylacetylene () and Compound (Scheme 3)

A mixture of compound 9a (286 mg, 1.13 mmol), phenylacetylene (6a) (230 mg, 2.25 mmol), n class="Chemical">CuSO4 5H2O (28 mg, 0.11 mmol) and granular copper (143 mg, 2.25 mmol) in DMF (5 mL) was stirred in darkness at room temperature for 60 min. To the resulting brown-green suspension (NH4)2CO3 (324 mg, 3.38 mmol) and water (3 mL) were added and stirring was continued for 10 min. The resulting mixture was diluted with 10% ethanol in chloroform (10 mL). The organic layer was separated and the aqueous layer was extracted with chloroform (3 × 10 mL). The combined organic layers were passed through a narrow (1 cm in diameter) column of silica gel (13 g) and the column was subsequently washed with 10% ethanol in chloroform (210 mL) using overpressure to the top of the column. The yellow eluate was washed with saturated aqueous NH4Cl (1 × 50 mL) and distilled water (1 × 50 mL), dried (Na2SO4), filtered, and evaporated to dryness. Trace amounts of DMF were removed by five subsequent co-destilations in vacuo at 50 °C with toluene (40 mL). The residue was chromatographed on a column of silica gel (30 g) using 38% ethyl acetate in hexane. The resulting white solid (88 mg) was crystallized from benzene affording triazole 7a (66 mg, 0.19 mmol, 16%), which was identified with the compound 7a described above.

3.15. 3-Azido-1-((1-Benzyl-1H-1,2,3-Triazol-4-yl)Methyl)-3-Methylquinoline-2,4(1H,3H)-Dione () (Scheme 3)

A mixture of acetylene 9a (254 mg, 1.0 mmol), n class="Chemical">(azidomethyl)benzene (8a) (266 mg, 2.0 mmol), CuSO4∙5H2O (25 mg, 0.1 mmol) and granular copper (127 mg, 2.0 mmol) in DMF (10 mL) was stirred at room temperature for 21 h. Then (NH4)2CO3 (288 mg, 3.0 mmol) and water (3 mL) were added and the stirring was continued for 10 min. The resulting mixture was poured into a narrow (1 cm in diameter) column of silica gel (13 g). The organic portion was eluted with 10% ethanol in chloroform (190 mL). The yellow eluate was washed with saturated aqueous NH4Cl (50 mL) and water (50 mL), dried (Na2SO4), filtered, and evaporated to dryness. Trace amounts of DMF were removed by six subsequent co-destilations in vacuo at 50 °C with toluene (30 mL). The residue was dissolved in chloroform (5 mL) and chromatographed on silica gel (35 g) column using gradually 38% and 50% ethyl acetate in petroleum ether as mobile phase, affording product 10a (164 mg, 0.42 mmol, 42%) as a white solid, m.p. 42–47 °C; Rf = 0.21 (38% ethyl acetate in petroleum ether); 1H NMR (500 MHz, CDCl3) δ 1.73 (s, 3H), 5.20 (d, 1H, J = 15.6 Hz), 5.31 (d, 1H, J = 15.6 Hz), 5.45 (d, 1H, J = 14.8 Hz), 5.49 (d, 1H, J = 14.8 Hz), 7.16–7.28 (m, 3H), 7.32–7.39 (m, 3H), 7.54 (s, 1H), 7.67 (ddd, 1H, J = 8.3, 7.4, 1.6 Hz), 7.77 (d, 1H, J = 8.4 Hz), 7.96 (dd, 1H, J = 7.7, 1.5 Hz); 13C NMR (126 MHz, CDCl3) δ 23.6, 39.1, 54.5, 70.6, 116.6, 119.5, 123.5, 124.3, 128.3, 128.8, 129.0, 129.3, 134.3, 137.1, 141.4, 143.0, 169.8, 191.3; IR (cm−1): ν 3137, 3033, 2980, 2106, 1713, 1676, 1602, 1489, 1469, 1379, 1336, 1279, 1223, 765, 724; HRMS (ESI+): m/z calcd for C20H18N7O2+ [M + H]+ 388,1516, found 388.1514. Anal. Calcd for C20H17N7O2 (387.39): C, 62.01; H, 4.42; N, 25.31%. Found: C, 61.74; H, 4.77; N, 25.15%.

4. Conclusions

We have developed a methodology for accessing bis(1,2,3-triazole) functionalized n class="Chemical">quinoline-2,4-diones in which the triazole heterocycles are present in substituents at positions 1 and 3 of the quinoline scaffold. Preliminary investigation has revealed that these compounds are potential multidentate ligands for arene-ruthenium.