Reactivity of 2-ethoxyquinazolin- 4-yl hydrazine and its use in synthesis of novel quinazoline derivatives of antimicrobial activity.

The reactions of 2-ethoxy-4-hydrazinoquinazoline 2 with diethyl oxalate and ethyl chloroacetate gave 6-ethoxy-2H-[1,2,4]triazino[4,3-c]quinazoline-3,4-dione 3 and 6-ethoxy-2,3-dihydro-4H-[1,2,4]triazino[4,3-c]quinazolin-4-one 4 respectively. A series of 5-ethoxy-2-X-[1,2,4]triazolo[1, 5-c]quinazolines 5a-d was also produced by reacting 2 with the acid chlorides namely: benzoyl, crotonyl, cinnamyl and 2-furoyl chlorides via Dimroth rearrangement. Also, 2 reacted with ethyl chloroformate giving 6. Condensation of 2 with acetone gave Schiff base 7, and with monosaccharides gave the sugar hydrazones 8a-e which were thereafter acetylated giving the corresponding 9a-e. Cyclization of 8a-e by iron(III) chloride gave triazoloquinazolines 10a-e acyclic C-nucleosides which, by acetylation, afforded 11a-e. All products were confirmed by elemental, IR, MS, and 1H-NMR analysis. Products 8-11 were chosen for biological screening test against gram(+ ive) and gram(- ive) bacteria.

1. Introduction

Quinazolines are a big family of heterocyclic compounds, which have shown broad variety of biological activity profiles, e. g. analgesic, antiinflammatory, antipyretic [1, 2], antimicrobial [3], anticonvulsant [4], anticancer [5], antitumoral [6], antihypertensive [7], antimalarial [8], diuretic [9], antidiabetic [10], antihistamine/sedative [11], antibiotic [12] and many others. Heterocycle-bearing n class="Chemical">N-glycosides are well known to play a significant role as inhibitors. An example is the tetrazole-bearing N-glycosides used as SGLT2 inhibitors [13], where their hypoglycemic activity is tested in vivo by mice oral glucose tolerance test (OGTT). Moreover, sugar hydrazones exhibit remarkable biological activity [14]. Herein we report the synthesis of hydrazones of D-exoses and D-pentoses with 4-hydrazinoquinazoline and the screening of their antimicrobial potentials.

2. Result and Discussion

Recently, it was reported that 4-substituted-aminoquinazolines are exploited as potent antitumor compounds [15]. The n class="Chemical">4-hydrazinoquinazolines resemble primary amines in being good substrates for aldehydes, ketones, alkyl and acid halides, anhydrides, etc. Therefore, they play a significant role in the synthesis of biologically active products [16]. The tautomeric behavior of hydrazinoquinazoline is used whenever necessary. For example, any necessary cyclization prior to product formation requires the presence of iminamine rather than hydrazine - form (Chart 1).

Chart 1

Tautomeric phenomenon of compound 2

Compound 2 reacted with diethyl oxalate and with n class="Chemical">ethyl chloroacetate in boiling ethanol to giving products 3 and 4 respectively (Scheme 1). The reaction possibly started with a nucleophilic attack of NH2 of hydrazine moiety on C=O of the ester group through a tetrahedral mechanism intermediate to yield a fleeting acyl derivative followed by 1,3-tautomerism and ring closure via SN2 mechanism.

Scheme 1

synthetic pathway for compounds 3 and 4

Similarly, compound 2 was reacted with acid halides namely: benzoyl, crotonyl, cinnamyl and furoyl chlorides in dry CHCl3 and K2CO3 giving the 2-acyl-1-(2-ethoxyquinazolin-4-yl)hydrazine derivatives, which tautomerized into the iminamide form upon heating and then underwent cyclization and Dimroth rearrangement affording the more stable derivatives 5a-d respectively (Scheme 2). Compound 2 was also reacted with ethyl chloroformate in dry pyridine affording derivative 6.

Scheme 2

synthetic pathway for compounds 5a-d

Compound 2 was reacted with acetone affording derivative 7, whose mass spectrum showed a molecular ion peak at m/z 244,246 whereas the 1n class="Chemical">NMR spectrum showed a singlet at δ 2.40 ppm characteristic for CH3 groups of the hydrazone. A number of sugar hydrazones 8a-e were prepared by condensation of compound 2 with equimolar amounts of D-aldohexoses and D-aldopentoses namely: glucose, galactose, mannose, xylose and arabinose, respectively in boiling ethanol and drops of acetic acid as a catalyst (Scheme 3). Their IR spectra revealed characteristic absorption bands at 3459-3135 cm-1 attributed to OH and NH groups. Acetylation of these hydrazones 8a-e by acetic anhydride in pyridine at room temperature afforded the corresponding per-acetyl products 9a-e, whose IR spectra revealed disappearance of the bands of OH groups and appearance of absorption bands in the carbonyl group frequency region at 1711-1725 cm-1 and 1673 - 1692 cm-1 due to the OAc and NAc groups, respectively. The 1H-NMR spectra showed signals corresponding to O-acetyl groups in addition to NAc groups; whereas no signals could be found for NH groups confirming that per-O- and N-acetylation had taken place. The spectra also confirmed the presence of the HC=N proton as a doublet at δ 6.55-6.74 ppm low field in addition to the rest of alditol-1-yl side chain.

Scheme 3

synthetic pathway for compounds 7 - 11

The mass spectral data of 9e showed a molecular ion peak at m/z 546, 548 which agreed with the molecular formula C25H30N4O10. The ion at m/z 215, 217 confirmed a loss of sugar residue from the molecular ion. The fragment at m/z 175, 177 referred to quinazoline ring (Scheme 4).

Scheme 4

MS data interpretation of compound 9a

The oxidative cyclization of the hydrazones 8a-e with ethanolic iron (III) chloride afforded the triazolo[4, 3-a]quinazolines 10a-e. The oxidation must have taken place by an electrophilic attack of the hard acid site of ferric chloride on the hardest basic site of sugar hydrazones 8a-e followed by an elimination of hydrogen chloride and formation of possibly a nitrilimine that undergoes 1,5-electrocyclization to give 10a-e. The IR spectra showed bands at 3240-3488 cm-1 (OH) and the mass spectral data of 10a showed a molecular ion peak at m/z 364 and 366 and an ion peak at m/z 214 and 216 presumably attributable to the triazoloquinazoline ring (Scheme 5).

Scheme 5

MS data interpretation of compound 10a

The 1H-n class="Chemical">NMR spectrum of compound 10c showed a doublet at low field at δ 5.22 ppm assigned to H-1, followed by the rest of the alditol-1-yl chain at higher field. The spectrum of 10e is similar, showing a doublet at low field at δ 5.03 ppm for H-1. Acetylation of 10a-e by acetic anhydride in pyridine at room temperature gave polyacetoxyalkyl derivatives 11a-e, whose IR spectra showed only one absorption band in the C=O frequency region (OA). The OAc groups were confirmed by the 1H-NMR spectra showing singlets at δ 2.03-2.19. The doublets at δ 5.74-6.02 were attributed to H-1. The mass spectra of products 11b and 11d showed molecular ion peaks at m/z 574, 576 and 501, 503 (Scheme 6) which, on combination with the elemental analysis, led to the assignment of their molecular formulas C26H30N4O11 and C23H26N4O9 respectively. In addition, the characteristic fragment at m/z 214,216 was shown attributable to the triazoloquinazoline ring.

Scheme 6

MS data interpretation of compound 11b

2.1 Antimicrobial Activity

All compounds were screened for their antimicrobial activity. Compounds 8-11 were tested against gram-positive bacteria Staphylococcus aureus, n class="Species">Streptobacillus moniliformis and Bacillus subtillis and gram-negative bacteria E. coli, Streptobacillus moniliformis and Pseudomonas acru- ginosa species applying the agar plate diffusion method. The screening results (Table 1) indicated that all the tested products exhibited antimicrobial activities against one or more type of bacteria. Almost all triazoloquinazoline products 10a-e and 11a-e showed more inhibition against the gram positive bacteria specially Streptobacillus than the gram negative one.

Table 1

Antimicrobial activity

Compd No	Gram-positive Bacteria			Gram-negative Bacteria
	Staphylococcussp	Streptobacillussp	Bacillussubtillissp	Eschcolisp	Streptobacillusussp	Pseudomonassp
8a	-	+	-	-	-	-
8b	-	+	-	-	-	-
8c	-	+	+	-	-	-
8d	-	+	-	-	-	-
8e	-	+	-	-	-	-
9a	-	+	+	-	+	-
9b	-	+	+	+	-	-
9c	-	+	+	-	-	+
9d	-	+	-	+	-	-
9e	-	+	+	+	-	+
10a	-	+	+	+	-	-
10b	-	+	+	+	+	+
10c	-	++	++	+	+	+
10d	+	+++	++	+	-	-
10e	+	+	+	+	-	-
11a	-	+++	++	+	+	+
11b	-	++	+	+	-	-
11c	-	++	+	+	-	-
11d	+	+	+	+	-	-
11e	-	++	+	+	-	-

2.2 Experimental

All melting points recorded are uncorrected. The IR spectra were recorded on a Pye Unicam SP1200 spectrophotometer using KBr wafer technique. The 1H-n class="Chemical">NMR spectra were determined on a Varian FT-200 or Brucker AC-200 MHz instrument using TMS as an internal standard. Chemical shifts (δ) are expressed in ppm. The mass spectra were determined using MP model NS-5988 and Shimadzu single focusing mass spectrometer (70 eV). All the solvents used were of HPLC/AnalaR grade. All reagents were used as received from Alfa Aesar.

Synthesis of 2-Ethoxyquinazolin-4-ylhydrazine 1.

An emulsion of 4-chloro-2-ethoxyquinazoline 1 (0.01mol) and hydrazine hydrate (0.05 mol) in benzene (15 mL) was stirred for 2h. The benzene-insoluble gum obtained was treated and washed with water, dried and crystallized from ethanol affording reddish brown crystals of product 2. Evaporation of solvent from the benzene-soluble fraction afforded a residue which was rinsed with water and air dried. Crystallization of the residue from absolute ethanol afforded product 2.

2-Ethoxyquinazolin-4-ylhydrazine 2.

Yield 68%; m. p. 156-158°C. Anal. for C10H12N4O (M. wt. 204); Found: C, 58.86; H, 5.78; N, 27.45; Calcd: C, 58.82; H, 5.88; N, 27.45; IR υ (cm-1) 1620 (C=N), 3160 (NH), 3250, 3300 (NH2); MS: m/z [M+H]+ 204; 1H - NMR (DMSO-d6) δ 1.18 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.19 (q, 2H, CH2 of ethoxy J = 7.4), 4.95 (br. s, 3H, NH and NH2), 7.43 - 8.08 (m, 4H, ArH).

6-ethoxy-2H-[1,2,4]triazino[4,3-c]quinazoline-3,4-dione 3.

A mixture of 2 (2.04 g, 0.01 mol) and diethyl oxalate (1.46 g, 0.01 mol) in boiling ethanol (30 mL) was heated under reflux for 10 h. After cooling the separated solid was collected and recrystallized from THF to give white crystals of 3; m. p. 237-239 ºC; yield 58 %. Anal. for C12H10N4O3 (M. wt. 258); Found: C, 54.21; H, 3.56; N, 21.89; Calcd: C, 55.81; H, 3.88; N, 21.71; IR υ (cm-1) 1680 -1690 (C=O), 3275 (sec NH); MS: m/z [M+H]+ 258 (77%). 1H-NMR (DMSO-d6) δ 1.21 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.38 (q, 2H, CH2 of ethoxy J = 7.4), 7.21 -8.13(m, 5H, ArH nd NH), 10.20(s, 1H, NH, exchangeable).

6-ethoxy-2H-[1,2,4]triazino[4,3-c]quinazolin-3(4H)-one 4.

A mixture of 2 (2.04 g, 0.01 mol) and ethyl chloroacetate (1.22 g, 0.01 mol) in boiling n class="Chemical">ethanol (35 mL) was heated under reflux for 10 h. The solid that separated after cooling was recrystallized from dioxane affording light brown crystals of 4; m. p. 213-216 ºC; yield 58 %. Anal. for C12H12N4O2 (M. wt. 244); Found: C, 58.85; H, 4.53; N, 23.02; Calcd: C, 59.02; H, 4.92; N, 22.95; IR υ (cm-1) 1675 (C=O), 2993 (CH), 3312 (sec NH); MS: m/z [M+H]+ 244; 1H-NMR (DMSO-d6) δ 1.19 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 3.94, 4.30(m, 2H, CH2CO), 4.30 (q, 2H, CH2 of ethoxy J = 7.4), 7.01- 8.31 (m, 5H, ArH and NH of triazine), 9.96 (s, 1H, NH, exchangeable).

Synthesis of 5-ethoxy-2-substituted[1,2,4]triazolo[1,5-c]quinazoline 5a-d.

To a solution of derivative 2 (0.01mol) in dry chloroform (100 mL) containing anhydrous n class="Chemical">K2CO3 (1g) the acid chloride namely: benzoyl, crotonyl, cinnamyl and furoyl chlorides (0.015 mol) was added slowly. After the addition was complete, the mixture was stirred at room temperature for 30 min and then heated on a steam bath for1h. The mixture was filtered, evaporated and the crude product was collected and crystallized from the proper solvent affording product 5a-d.

5-Ethoxy-2-phenyl[1,2,4]triazolo[1,5-c]quinazoline 5a.

Colorless needles from ethanol; m. p. 168 -170ºC; yield 68%. Anal. for C17H14N4O (M. wt. 290); Found: C, 70.17; H, 4.91; N, 19.38; Calcd: C, 70.34; H, 4.83; N, 19.31; IR υ (cm-1) 1622 (C=N), 3050 (CH); MS: m/z [M+H]+ 290 (32.2), 292 (12.3), 214 (100), 216 (23.5), 174 (43.8), 176 (8.2), 78 (13.2), 80 (0.3); 1H-NMR (DMSO-d6) δ 1.19 (t, 3H, CH3 of ethoxy J = 7.4), 4.33 (q, 2H, CH2 of ethoxy J = 7.4), 7.57-8.10 (m, 5H, phenyl), 7.62 - 8.65 (m, 4H, ArH).

5-Ethoxy-2-[(1E)-prop-1-en-1-yl][1,2,4]triazolo[1,5-c]quinazoline 5b.

Brown white crystals from ethanol; m. p. 223-225 ºC; yield 71%. Anal. for C14H14N4O (M. wt. 254); Found: C, 66.28; H, 5.31; N, 22.23; Calcd: C, 66.14; H, 5.51; N, 22.05; IR υ (cm-1) 1635 (C=N), 3050 (CH); MS: m/z [M+H]+ 254 (48.2), 256 (14.2), 174 (100), 176 (38.1); 1H-NMR(DMSO-d6) δ 1.21(t, 3H, CH3 of ethoxy J = 7.4), 1.67 (t, 3H, CH3), 4.31(q, 2H, CH2 of ethoxy J = 7.4 Hz), 6.13 (d, H, CHtrans), 6.70 (d, H, CHtrans), 7.53 - 8.21 (m, 4H, ArH).

5-Ethoxy-2-[(E)-2-phenylethenyl][1,2,4]triazolo[1,5-c]quinazoline 5c.

Off-white crystals from ethanol; 153 - 155 ºC; yield 62%. Anal. for C19H16N4O (M. wt. 316); Found: C, 72.84; H, 5.19; N, 17.76; Calcd: C, 72.15; H, 5.06; N, 17.72; IR υ (cm-1) 1633(C=N), MS: m/z [M+H]+ 316 (29.3), 318 (12.8), 174 (100), 176 (41.1), 103 (12.7), 105 (0.8); 1H-NMR(DMSO-d6) δ 1.2(t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.38 (q, 2H, CH2 of ethoxy J = 7.4), 7.09, 7.48 (2d, 2H, of two olefin protons), 7.4-7.6 (m, 5H, PhH), 7.67-8.71 (m, 4H, quinazoline).

5-Ethoxy-2-(furan-2-yl)[1,2,4]triazolo[1,5-c]quinazoline 5d.

White crystals from benzene; 163-164ºC; yield 68%. Anal. for C15H12N4O2 (M. wt. 280); Found: C, 64.38; H, 4.31; N, 20.07; Calcd: C, 64.29; H, 4.29; N, 20.00; IR υ (cm-1) 1619 (C=N), MS: m/z [M+H]+ 280 (33.2), 282 (12.4), 174 (100), 176 (31.3), 60 (0.8), 61 (0.1); 1H-NMR(DMSO-d6) δ1.2 (t, 3H, CH3 of ethoxy J = 7.4Hz), 4.2 (q, 2H, CH2 of ethoxy J = 7.4), 6.79(dd, 1H, J = 3.6Hz, J = 1.6, Furan-H), 7.29(d, 1H, J = 4.4Hz, Furan-H), 7.76(d, 1H, J = 1.6Hz, Furan-H), 7.5 - 8.2 (m, 4H, ArH).

1-(2-Ethoxyquinazolin-4-yl)-2-bis(ethoxycarbonyl) hydrazine 6.

A mixture of 2 (0.01 mol) and ethyl chloroformate (0.02 mol) in dry n class="Chemical">pyridine (20 mL) was heated at boiling water bath for 4 h. The solvent was evaporated under vacuum, the residue was cooled and crystallized from ethanol giving colorless needles of 6; m.p. 123-125 ºC; yield 52 %. Anal. C16H20N4O5 (M.wt. 348); Found: C, 55.27; H, 5.83; N, 16.08; Calcd: C, 55.17; H, 5.75; N, 16.09; IR υ (cm-1) 1250 (C-O), 1622 (C=N), 1731 (C=O), 2986 (C-H); MS: m/z [M+H]+ 348 (31.5), 350 (14.1), 275 (2.8), 277 (13.2), 187 (0.8), 189 (0.2), 174 (100), 176 (39.4), 74 (0.7), 75(0.1); 1H-NMR(DMSO-d6) δ 1.11-1.25 (t, 9H, 3 CH3 of ethoxy), 4.15-4.25(q, 6H, 3 CH2 of ethoxy), 8.5-8.8(m, 4H, ArH), 10.05(s, 1H,NH).

2-ethoxy-4-hydrazinoquinazoline Acetone hydrazone 7.

A solution of crude 2 (0.01 mol) in acetone was left to stand for several days when the solvent had evaporated to give a solid from which the n class="Chemical">hydrazone 7 (80%) was isolated by chromatography on silica gel (30 g, 2.5% absolute ethanol-chloroform). Crystallization from hexane gave product 7 as colorless solid that turned deep yellow on exposure to light and air; m. p. 115 -116 ºC; yield 85 %. Anal. for C13H16N4O (M. wt. 244); Found: C, 63.98; H, 6.61; N, 22.95; Calcd: C, 63.93; H, 6.56; N, 22.95; IR υ (cm-1) 1634 (C=N), 2993 (CH), 3243 (sec NH); MS: m/z [M+H]+ 244 (33.1), 246 (12.6), 215 (100), 217 (19.6), 174 (55.8), 176 (1.2); 1H-NMR(DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4), 2.4 (3H, s, -N=C-CH3), 4.23(q, 2H, CH2 of ethoxy J = 7.4), 7.1-8.3(m, 4H, ArH), 8.3(br. s,1H, NH).

General procedure for the synthesis of sugar (2-ethoxyquinazolin-4-yl) hydrazones 8a-e.

To a suspension of 2-Ethoxy-4-hydrazinoquinazoline 2 (0.01 mol) in ethanol (30 ml), was added a solution of selected sugar (D-glucose, D-galactose, D-mannose, D-xylose and D-arabinose (0.01 mol)) in water (10 ml) and few drops of glacial acetic acid. The mixture was heated under reflux until reaction was judged complete by TLC (2-6 h). The solid product formed upon cooling was filtered off, washed with the minimum amount of ethanol, dried and finally crystallized from ethanol to afford the corresponding hydrazones 8a-e.

2-ethoxy-4-hydrazinoquinazoline-D-glucose hydrazone 8a.

Yield 62 % (from ethanol); m. p. 212 - 214 ºC; Anal. for C16H22N4O6 (M. wt. 366); Found: C, 52.66; H, 6.16; N, 15.41; Calcd: C, 52.46; H, 6.01; N, 15.30; IR υ (cm-1) 1615 (C=N), 3225 - 3417 (OH, NH); MS: m/z [M+H]+ 366; 1H-NMR (DMSO-d6) δ 1.17 (t, 3H, CH3 of ethoxy J = 7.4), 4.17 (q, 2H, CH2 of ethoxy J = 7.4), 7.1- 8.3 (m, 4H, ArH), 8.33 (br. s, 1H, NH).

2-ethoxy-4-hydrazinoquinazoline-D-galactose hydrazone 8b.

Yield 88% (from DMF/ethanol); m. p. 193-195 ºC; Anal. for C16H22N4O6 (M. wt. 366); Found: C, 52.56; H, 6.23; N, 15.48; Calcd: C, 52.46; H, 6.01; N, 15.30; IR υ (cm-1) 1615 (C=N), 3135-3391 (OH and NH); MS: m/z [M+H]+ 366; 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.21 (q, 2H, CH2 of ethoxy J = 7.4), 7.3 - 8.2 (m, 4H, ArH), 8.37 (br. s, 1H, NH).

2-ethoxy-4-hydrazinoquinazoline-D-mannose hydrazone 8c.

Yield 77% (from DMF/ethanol); m. p. 222-224ºC; Anal. for C16H22N4O6 (M. wt. 366); Found: C, 52.42; H, 6.04; N, 15.37; Calcd: C, 52.46; H, 6.01; N, 15.30; IR υ (cm-1) 1618 (C=N), 3232-3459 (OH and NH); MS: m/z [M+H]+ 366; 1H-NMR (DMSO-d6) δ 1.15 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.23 (q, 2H, CH2 of ethoxy J = 7.4), 7.0 - 8.1 (m, 4H, ArH), 8.29 (br. s, 1H, NH).

2-ethoxy-4-hydrazinoquinazoline-D-ribose hydrazone 8d.

Yield 61% (from DMF/ethanol); m. p. 217-219 ºC; Anal. for C15H20N4O5 (M. wt. 336); Found: C, 53.68; H, 6.04; N, 16.57; Calcd: C, 53.57; H, 5.95; N, 16.67; IR υ (cm-1) 1616 (C=N), 3210-3439 (OH and NH); MS: m/z [M+H]+ 336; 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.23 (q, 2H, CH2 of ethoxy J = 7.4), 7.1- 8.2 (m, 4H, ArH), 8.52 (br. s, 1H, NH).

2-ethoxy-4-hydrazinoquinazoline-D-arabinose hydrazone 8e.

Yield 63% (from ethanol); m. p. 197-198 ºC; Anal. for C15H20N4O5 (M. wt. 336); Found: C, 53.62; H, 5.98; N, 16.63; Calcd: C, 53.57; H, 5.95; N, 16.67; IR υ (cm-1) 1613 (C=N), 3230-3414 (OH and NH); MS: m/z [M+H]+ 336; 1H-NMR (DMSO-d6) δ 1.11 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 4.19 (q, 2H, CH2 of ethoxy J = 7.4), 7.2- 8.3 (m, 4H, ArH), 8.33 (br. s, 1H, NH).

Synthesis of per-O-acetylsugar [1-acetyl-1-(2-ethoxyquinazolin-4-yl)] hydrazones 9a-e.

A cold solution of 8a-e (0.02 mol) in dry pyridine (50 mL) was treated with Ac2O (50 mL). The mixture was kept overnight at room temperature, with occasional shaking, and then poured onto crushed ice, and the residue was collected by filtration, washed repeatedly with water, dried and recrystallized from ethanol affording product 9a-e.

2,3,4,5,6-Penta-O-acetyl-D-glucose[1-acetyl-1-(2-ethoxyquinazolin-4-yl)] hydrazones 9a.

Yield 58 %; m. p. 63 - 64 ºC; Anal. for C28H34N4O12 (M. wt. 618); Found: C, 54.41; H, 5.56; N, 9.01; Calcd: C, 54.37; H, 5.50; N, 9.06; IR υ (cm-1) 1608 (C=N), 1673 (NAc), 1718 (OAc); MS: m/z [M+H]+ 618; 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 2.02, 2.04, 2.10 (3s, 15H, 5 OAc), 2.50 (s, 3H, NAc), 4.1(q, 2H, CH2 of ethoxy J = 7.4),4.15 (dd, 1H, H-6’), 4.26 (dd, 1H, H-6), 5.02-5.10 (m, 1H, H-5), 5.44-5.55 (m, 2H, H-4, H-3), 5.62 (dd, 1H, H-2), 6.74 (d, 1H, H-1), 7.11-8.23 (m, 4H, ArH).

2,3,4,5,6-Penta-O-acetyl-D-galactose[1-acetyl-1-(2-ethoxyquinazolin-4-yl)] hydrazones 9b.

Yield 80 %; m. p. 158 -160 ºC; Anal. for C28H34N4O12 (M. wt. 618); Found: C, 54.43; H, 5.53; N, 9.03; Calcd: C, 54.37; H, 5.50; N, 9.06; IR υ (cm-1) 1633(C=N), 1692(NAc), 1722(OAc); MS: m/z [M+H]+ 618; 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 1.96, 1.99, 2.02, 2.03, 2.08, 2.09 (5s, 15H, 5OAc), 2.47(s, 3H, NAc), 3.88(dd, 1H, H-6’), 4.1(q, 2H, CH2 of ethoxy J = 7.4), 4.28 (dd, 1H, H-6), 5.38-5.88 (m, 4H, H-5, H-4, H-3, H-2), 6.55 (d, 1H, H-1), 7.15- 8.33 (m, 4H, ArH).

2,3,4,5,6-Penta-O-acetyl-D-mannose[1-acetyl-1-(2-ethoxyquinazolin-4-yl)] hydrazones 9c.

Yield 63 %; m. p. 58 - 60 ºC; Anal. for C28H34N4O12 (M. wt. 618); Found: C, 54.40; H, 5.51; N, 9.02; Calcd: C, 54.37; H, 5.50; N, 9.06; IR υ (cm-1) 1615(C=N), 1682(NAc), 1711(OAc); MS: m/z [M+H]+ 618; 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4 Hz), 2.05, 2.06, 2.10 (3s, 15H,5OAc), 2.52 (s, 3H, NAc), 4.11(q, 2H, CH2 of ethoxy J = 7.4), 4.14 (dd, 1H, H-6’), 4.28 (dd, 1H, H-6), 5.22-5.40 (m, 1H, H-5), 5.42 (d, 1H, H-4), 5.54 (dd, 1H, H-3), 5.66 (dd, 1H, H-2), 6.68 (d, 1H, H-1), 7.00 - 8.13 (m, 4H, ArH).

2,3,4,5-Tetra-O-acetyl-D-ribose[1-acetyl-1-(2-ethoxyquinazolin-4-yl)] hydrazones 9d.

Yield 52 %; m. p. 92 - 93 ºC; Anal. for C25H30N4O10 (M. wt. 546); Found: C, 54.97; H, 5.54; N, 10.29; Calcd: C, 54.94; H, 5.49; N, 10.26; IR υ (cm-1) 1619 (C=N), 1682 (NAc), 1725 (OAc); MS: m/z [M+H]+ 546; 1H-NMR (DMSO-d6) δ 1.91, 1.94, 2.00, 2.19 (4s, 12H, 4OAc), 1.13 (t,3H, CH3 of ethoxy J = 7.4 Hz), 2.51 (s, 3H, NAc), 4.15 (q, 2H, CH2 of ethoxy J = 7.4), 4.22 (dd, 1H, H-5’), 4.39 (dd, 1H, H-5), 5.38 - 5.40 (m, 1H, H-4), 5.78 (dd, 1H, H-3), 6.01 (dd, 1H, H-2), 6.59 (d, 1H, H-1), 7.10- 8.32 (m, 4H, ArH).

2,3,4,5-Tetra-O-acetyl-D-arabinose[1-acetyl-1-(2-ethoxyquinazolin-4-yl)] hydrazones 9e.

Yield 67 %; m. p. 108-111 ºC; Anal. for C25H30N4O10 (M. wt. 546); Found: C, 54.95; H, 5.52; N, 10.27; Calcd: C, 54.94; H, 5.49; N, 10.26; IR υ (cm-1) 1610 (C=N), 1682 (NAc), 1715 (OAc); MS: m/z [M+H]+ 546 (42.9), 548 (14.3), 504 (10.5), 506 (3.4), 444 (25.0), 446 (8.2), 401 (13.3), 403 (4.4), 341 (17.6), 343 (5.8), 257 (40.5), 259 (13.4), 215 (100), 217 (33.3), 175 (16.2), 177 (5.3), 157 (2.8), 159 (0.9), 130 (58.3), 132 (0.1).

General method for preparing 1-(alditol-1-yl) - 5-ethoxy[1,2,4]triazolo[1,5-c] quinazoline 10a-e.

A 2 M solution of iron (III) chloride in EtOH (2 mL) was added dropwise to a boiling solution of 8a-e (0.01 mol) in ethanol (50 mL). Heating was continued for 10 min and the mixture was then kept overnight at room temperature. The product was filtered, washed repeatedly with water, air dried and recrystallized from EtOH affording product 10a-e.

1-(D-gluco-pentitol-1-yl)-5-ethoxy[1,2,4]triazolo[1,5-c] quinazoline 10a.

Yield 90 %; m. p. 85-87 ºC; Anal. for C16H20N4O6 (M. wt. 364); Found: C, 52.79; H, 5.52; N,15.43; Calcd: C, 52.75; H, 5.49; N, 15.38; IR υ (cm-1) 1613 (C=N), 3240-3454 (OH); MS: m/z [M+H]+ 364 (14.4), 366 (4.8), 333 (0.3), 335 (0.1), 303 (0.6), 305 (0.2), 273 (0.6), 275 (0.2), 214 (100), 216 (33.4), 187 (59.8), 189 (19.6), 175(6.2), 177 (2.1), 157 (2.5), 159 (0.5), 130(63.4), 132 (0.1).

1-(D-galacto-pentitol-1-yl)-5-ethoxy[1,2,4]triazolo[1,5-c] quinazoline 10b.

Yield 85 %; m. p. 80 ºC; Anal. for C16H20N4O6 (M. wt. 364); Found: C, 52.77; H, 5.56;N, 15.48; Calcd: C, 52.74; H, 5.49; N, 15.38; IR υ (cm-1) 1619 (C=N), 3340-3450 (OH);

1-(D-manno-pentitol-1-yl)-5-ethoxy[1,2,4]triazolo[1,5-c] quinazoline 10c.

Yield 75 %; m. p. 101-102ºC; Anal. for C16H20N4O6 (M. wt. 364); Found: C, 52.82; H, 5.59; N, 15.53; Calcd: C, 52.74; H, 5.49; N, 15.38; IR υ (cm-1) 1615 (C=N), 3290-3466 (OH); 1H-NMR (DMSO-d6) δ 3.97-4.20 (m, 2H, H-5’, H-5), 4.40 (dd, 1H, H-4), 4.62 (dd, 1H, H-3), 5.03 (t, 1H, H-2), 5.22 (d, 1H, H-1), 7.10- 8.32 (m, 4H, ArH).

1-(D-ribo-pentitol-1-yl)-5-ethoxy[1,2,4]triazolo[1,5-c] quinazoline 10d.

Yield 68 %; m. p. 128 ºC; Anal. for C15H18N4O5 (M. wt. 334); Found: C, 53.92; H, 5.43; N, 16.81; Calcd: C, 53.89; H, 5.39; N, 16.77; IR υ (cm-1) 1623 (C=N), 3310 - 3444 (OH); MS: m/z [M+H]+ 334 (21.1), 336 (7.0), 303 (3.5), 305 (1.1), 273 (0.6), 275 (0.2), 214 (9.9), 216 (3.2), 187 (100), 189 (33.2), 175 (5.4), 177 (1.1), 157 (1.8), 159 (0.3), 130(56.4), 132 (0.1).

1-(D-arabino-pentitol-1-yl)- 5-ethoxy[1,2,4]triazolo[1,5-c] quinazoline 10e.

Yield 63 %; m. p. 108 ºC; Anal. for C15H18N4O5 (M. wt. 334); Found: C, 53.97; H, 5.46; N, 16.88; Calcd: C, 53.89; H, 5.39; N, 16.77; IR υ (cm-1) 1619 (C=N), 3320-3480 (OH); 1H-NMR (DMSO-d6) δ 3.49-3.75 (m, 2H, H-4’, H-4), 4.18-4.39 (m, 2H, H-3, H-2), 5.03 (d, 1H, H-1),7.1-8.3 (m, 4H, ArH).

Preparation of 1-(penta-O-acetylsugar-1-yl)-5-ethoxy-1,2,4-triazolo[1,5-c] quinazoline 11a-e

A cold solution of 10a-e (0.002 mol) in dry pyridine (10 mL) was treated with Ac2O (6 mL), and the mixture was kept overnight at room temperature, with occasional shaking, and then poured onto crushed ice, and the residue was collected by filtration, washed repeatedly with water, dried and recrystallized from ethanol affording product 11a-e.

1-(1,2,3,4,5-penta-O-acetyl-D-glucopentitol-1-yl)-5-ethoxy-1,2,4-triazolo[1,5-c] quinazoline 11a.

Yield 78 %; m. p. 71 ºC; Anal. for C26H30N4O11 (M. wt. 574); Found: C, 54.42; H, 5.26; N, 9.83; Calcd: C, 54.36; H, 5.23; N, 9.76; IR υ (cm-1) 1650 (C=N), 1725 (OAc); 1H-NMR (DMSO-d6) δ 1.99, 2.01, 2.03 (3s, 12H, 4OAc), 3.98 (dd, 1H, H-5’), 4.30 (dd, 1H, H-5), 5.30-5.52 (m, 3H, H-4, H-3, H-2), 5.86 (d, 1H, H-1), 7.26-8.30 (m, 4H, ArH).

1-(1,2,3,4,5-penta-O-acetyl-D-galactopentitol-1-yl)-5-ethoxy-1,2,4-triazolo[1,5-c] quinazoline 11b.

Yield 81 %; m. p. 66 ºC; Anal. for C26H30N4O11 (M. wt. 574); Found: C, 54.39; H, 5.24; N, 9.79; Calcd: C, 54.36; H, 5.23; N, 9.76; IR υ (cm-1) 1619(C=N), 1719(OAc); MS:m/z [M+H]+ 574 (19.3), 576 (6.3), 501 (27.4), 503(9.1), 429(31.7), 431 (10.5), 315 (9.5), 317 (3.2), 214 (100), 216 (33.3), 187 (59.8), 189 (19.9), 175(5.4), 177 (2.1), 157 (1.3), 159 (0.2), 130 (48.4), 132 (0.1).

1-(1,2,3,4,5-penta-O-acetyl-D-mannopentitol-1-yl)-5-ethoxy-1,2,4-triazolo[1,5-c]quinazoline 11c.

Yield 63 %; m. p. 76 ºC; Anal. for C26H30N4O11 (M. wt. 574); Found: C, 54.41; H, 5.27;N, 9.81; Calcd: C, 54.36; H, 5.23; N, 9.76; IR υ (cm-1) 1639 (C=N), 1745 (OAc); 1H-NMR (DMSO-d6) δ1.96, 1.99, 2.03, 2.08(4s, 12H, 4OAc), 3.90(dd, 1H, H-5’), 4.32 (dd, 1H, H-5), 5.30-5.53 (m, 3H, H-4, H-3, H-2), 5.76 (d, 1H, H-1), 7.15-8.31(m, 4H, ArH).

1-(1,2,3,4-tetra-O-acetyl-D-ribopentitol-1-yl)-5-ethoxy-1,2,4-triazolo[1,5-c] quinazoline 11d.

Yield 58 %; m. p. 71 ºC; Anal. for C23H26N4O9 (M. wt. 502); Found: C, 54.94; H, 5.22; N, 11.14; Calcd: C, 54.98; H, 5.18; N, 11.16; IR υ (cm-1) 1629 (C=N), 1731 (C=O); MS: m/z [M+H]+ 502 (21.3), 504 (7.1), 430 (17.6), 432 (5.8), 358 (21.4), 360 (7.1), 286(16.9), 288(5.6), 214 (100), 216 (33.2), 187(8.4), 189(2.8), 175(5.8), 177(1.9), 157(1.6), 159 (0.1), 130 (59.3), 132 (0.1). 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4), 2.03, 2.06, 2.08 (3s, 12H, 4OAc), 4.05 (dd, 2H, H-4’, H-4), 4.35-4.55 (m, 1H, H-3), 5.56(dd, 1H, H-2), 5.74 (d, 1H, H-1), 7.1 - 8.3 (m, 4H, ArH).

1-(1,2,3,4-tetra-O-acetyl-D-arabinopentitol-1-yl)-5-ethoxy-1,2,4-triazolo[1,5-c] quinazoline 11e. Yield 67%; m. p. 98ºC; Anal. for C23H26N4O9 (M. wt. 502); Found: C, 54.92; H, 5.24; N, 11.19; Calcd: C, 54.98; H, 5.18; N, 11.16; IR υ (cm-1) 1618 (C=N); 1H-NMR (DMSO-d6) δ 1.13 (t, 3H, CH3 of ethoxy J = 7.4), 1.81, 1.86, 1.91, 2.19 (4s, 12H, 4 OAc), 4.22 (dd, 2H, H-4’, H-4), 5.35 - 5.41 (m, 1H,H-3), 5.76 (dd, 1H, H-2), 6.02 (d, 1H, H-1), 7.17 - 8.32 (m, 4H, ArH).