HOAc-Mediated Domino Diels-Alder Reaction for Synthesis of Spiro[cyclohexane-1,3'-indolines] in Ionic Liquid [Bmim]Br.

An efficient and diastereoselective synthetic protocol for the construction of spiro[cyclohexane-1,3'-indolin]-3-en-2'-ones and spiro[cyclohexane-1,2'-inden]-3-ene-1',3'-diones was provided by HOAc-mediated domino reaction of pinacoles with typical dienophiles, such as 3-methyleneoxindolines and 2-arylideneindane-1,3-diones, in ionic liquid [Bmim]Br. This domino reaction involved the in situ generation of 1,3-dienes from acid-mediated dehydration of various pinacoles and the sequential Diels-Alder reaction.

Introduction

Spiro[cyclohexane-1,3′-indoline] is one of the most privileged motifs, which is not only featured in many naturally occurring alkaloids but also exists in various synthetic pharmaceutical compounds, displaying a broad spectrum biological activity, such as antimicrobial, anticancer, and anti-inflammatory activity.[1] For example, gelsemine is an effective agent for treatment of both neuropathic pain and sleep disturbance in partial sciatic nerve ligation mice. Satavaptan shows a good effect on maintaining normal sodium level. The NITD 609 shows pharmacokinetic properties in the treatment of a rodent malaria model (Figure ).[2] Therefore, the development of efficient methodology for the construction of spiro[cyclohexane-1,3′-indoline] has attracted continual interest.[3,4] In the past years, many elegant works have been developed for the synthesis of diverse spiro[cyclohexane-1,3′-indolines].[5] Among various strategies for the construction of spiro[cyclohexane-1,3′-indoline], the Diels–Alder reaction between various dienes and 3-methyleneindolinones is the most effective method on the basis of the high diastereoselectivity and enantioselectivity of the concerted Diels–Alder reaction.[6] For example, Inoue reported the Diels–Alder reaction for the synthesis of spirooxindole utilizing 1,3-pentadiene and 3-methyleneoxindolines. One of the products, ethyl 6′-bromo-2-methyl-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate, is the key intermediate in the total synthesis of neosurugatoxin.[7]

Figure 1

Some biologically active spiro[cyclohexane-1,3′-indolines].

The 2-vinylindole or 3-vinylindole constantly acts as diene in the [4 + 2] cycloaddition reaction for the construction of spiro[cyclohexane-1,3′-oxindolines].[8] Melchiorre[9] and Chen[10] described asymmetric Diels–Alder reaction using methyleneoxindole with in situ generated dienes such as heterocyclic ortho-quinodimethanes and 2,4-dienals to afford spirooxindoles. Joergensen reported enantioselective Diels–Alder reaction of trienamines with 3-methyleneoxindoles, yielding functionalized spiro[cyclohexane-1,3′-oxindole] derivatives.[11] Gong also developed bifunctional organocatalytic asymmetric [4 + 2] cycloaddition of Nazarov reagents, and methyleneindolinones afforded spirooxindoline derivatives in excellent yield with excellent diastereo- and enantioselectivity.[12] Recently, we successfully developed a TfOH-catalyzed one-pot domino reaction of indoles, acetophenones, and 3-methyleneoxindolines for the synthesis of tetrahydrospiro[carbazole-1,3′-indolines], in which the in situ generated reactive 3-alkenylindole and its sequential Diels–Alder reaction were the key steps (Scheme ).[13] The reactive 1,3-diene could be prepared by the dehydration of pinacoles under controlled reaction conditions.[14] More importantly, several sustainable selective dehydration of pinacol derivatives to branched 1,3-dienes could be carried out in a solid acid/ionic liquid catalyst system, such as Amberlyst-15/[Emim]Cl and tetrabutylphosphonium bromide.[15] We envisioned that spiro[cyclohexane-1,3′-indoline] framework could be formed via a Diels–Alder reaction between 3-methyleneoxindolines and the in situ generated diene from butane-2,3-dioles under suitable conditions. To show the synthetic values of this efficient one-pot domino reaction, herein, we wish to reveal an efficient and diastereoselective synthetic protocol for the construction of spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones and spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-diones by HOAc-mediated domino reaction of pinacoles with typical dienophiles such as 3-methyleneoxindolines and 2-arylideneindane-1,3-diones in ionic liquid [Bmim]Br.

Scheme 1

Synthetic Strategy of Generation of Dienes and the Diels–Alder Reaction

Results and Discussion

Initially, the reaction conditions were examined using equivalent pinacol and 3-methyleneoxindoline 1-benzyl-3-[2-oxo-2-(p-tolyl)ethylidene]indolin-2-one as substrates in ionic liquid [Bmim]Br. No reaction was observed when heating the two substrates in the [Bmim]Br at about 120 °C.[15] When formic acid was added as catalyst, the expected spirooxindole 1a was obtained in 41% yield and the starting material 1-benzyl-3-[2-oxo-2-(p-tolyl)ethylidene]indolin-2-one was also recovered in about 40% yield. After adjusting the ratio of pinacol to 1-benzyl-3-[2-oxo-2-(p-tolyl)ethylidene]indolin-2-one to 2:1, the product 1a was still obtained in moderate yield and a reduced 1-benzyl-3-[2-oxo-2-(p-tolyl)ethyl]indolin-2-one was separated from the system in 34% yield. It is obvious that formic acid reacted as a reducing reagent to cause the partial reduction of 1-benzyl-3-[2-oxo-2-(p-tolyl)ethylidene]indolin-2-one. When the reaction was performed in [Bmim]Br in presence of acetic acid (25%), the target spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones 1a was successfully obtained in satisfactory yield (86%) and the reduced product was not observed. Reducing the amount of acetic acid and carrying out the reaction at lower temperature would greatly reduce the yields of 1a. Thus, optimized reaction conditions were successfully obtained.

Under the optimized conditions, a variety of substrates was then examined (Table ). The reaction between pinacol and various substituted 3-phenacylideneoxindolines proceeded smoothly to give spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones 1a–f in 72–86% yields. The pinacol derivatives, such as 2,3-diphenylbutane-2,3-diol and 2,3-di(p-tolyl)butane-2,3-diol, were also employed in the reaction to give the expected functionalized spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones 1g–m in 73–85% yields. The two phenyl groups in the substrates did not cause an unfavorable effect on the domino Diels–Alder reaction. It can be seen that the substituents on 3-phenacylideneoxindolines have a little effect on yields of products. The structures of the obtained spiro compound products 1a–m were fully characterized by IR, high-resolution mass spectrometry (HRMS), 1H NMR, and 13C NMR spectra. Because there are two adjacent chiral carbon atoms in the newly formed cyclohexenyl ring, the cis/trans-diastereoisomers could be formed in the reactions. 1H NMR spectra showed that only one set of characterized signals was observed for the typical groups in the molecule. The single-crystal structure of 1a (Figure ), 1g, and 1h (Figures S1 and S2) was successfully determined by single X-ray diffraction. The three compounds have the same relative configuration. From Figure , it can be seen that the phenacyl group and the phenyl group of oxindoline moiety stand at cis-position. It has been known that the phenacyl group usually exists at cis-position to the phenyl group of the oxindoline moiety in 3-phenacylideneoxindoline.[16] Thus, the cis-configuration was retained in the domino reaction, which also indicated that the reaction proceeded according to the concerted Diels–Alder reaction mechanism.

Table 1

Synthesis of Spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones 1a–ma,b

Reaction conditions: pinacol (1.0 mmol), 3-phenacylideneoxindole (0.5 mmol), [Bmim]Br (2.0 mL), HOAc (0.5 mL), 15 h.

Isolated yield.

Figure 2

Crystal structure of compound 1a.

For developing the scope of the reaction, another common 3-methyleneoxindolines, ethyl (E)-2-(2-oxoindolin-3-ylidene)acetates were employed in the reaction under the same conditions. The results are summarized in Table . The expected functionalized spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones 2a–g were successfully obtained in 69–83% yields. It should be pointed out that the oxindolines without N-substituent reacted well to give spiro compounds 2f and 2g in good yields. The structures of obtained spiro [cyclohexane-1,3′-indolin]-3-en-2′-ones 2a–g were established on various spectroscopies. Additionally, the single-crystal structure of compound 2b (Figure ) was confirmed by X-ray diffraction. The single-crystal structure of compound 2b clearly demonstrated that the ethoxycarbonyl group and the phenyl group of oxindoline moiety exist in cis-position. Thus, the spiro compound 2b has the same relative configuration as that of above-mentioned compounds 1a, 1g, and 1h. This result also indicated the acid-mediated domino reaction has a high diastereoselectivity.

Table 2

Synthesis of Spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones 2a–ga,b

Reaction conditions: pinacol (1.0 mmol), 3-methylideneoxindole (0.5 mmol), [Bmim]Br (2 mL), HOAc (0.5 mL), 15 h.

Isolated yield.

Figure 3

Crystal structure of compound 2b.

For exploring the synthetic value of the reaction, 2-arylideneindane-1,3-diones were also employed in the reaction. The acid-mediated domino reaction of 2,3-diarylpinacols with 3-phenacylideneoxindoles in [Bmim]Br afforded the expected spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-diones 3a–h in moderate to good yield. The results are summarized in Table . The relative lower yields were due to partial decomposition of 2-arylideneindane-1,3-diones in acidic medium at high temperature. The obtained products 3a–h were also characterized by the IR, HRMS, 1H, and 13C NMR spectroscopies. To confirm the structure of product, the single-crystal structure of spiro compound 3d was determined by X-ray diffraction analysis (Figure ).

Table 3

Synthesis of Spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-diones 3a–ha,b

Reaction conditions: pinacol (1.0 mmol), 2-arylidene-1,3-indanedione (0.5 mmol), [Bmim]Br (2 mL), HOAc (0.5 mL), 15 h.

Isolated yield.

Figure 4

Crystal structure of compound 3d.

Conclusions

In summary, we have studied in situ generation of dienes from acid-mediated dehydration of various pinacoles in ionic liquid [Bmim]Br and a sequential Diels–Alder reaction with typical dienophiles such as 3-methyleneoxindolines and 2-arylidene-1,3-indanediones. This domino reaction not only provided the efficient synthetic methodology for 1,3-dienes but also developed a novel synthetic protocol for the construction of spiro[cyclohexane-1,3′-indolin]-3-en-2′-ones and spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-diones. The advantages of this domino reaction included readily available starting materials, simple reaction conditions, broad scope of substrates, satisfactory yields, and high diastereoselectivity, which will enable it to find potential applications in synthetic and medicinal chemistry.

Experimental Section

General Procedure for the Domino Diels–Alder Reaction

To a solution of ionic liquid ([Bmim]Br) (2.0 mL) were added pinacol (1.0 mmol), 3-phenacylideneoxindole or 2-arylidene-1,3-indanedione (0.5 mmol), and acetic acid (0.5 mL) in a 10 mL tube; the mixture were heat at 120 °C for 15 h. After cooling to room temperature, the mixture was poured into water (50.0 mL). The organic layer was extracted with ethyl acetate and dried with anhydrous Na2SO4. After removing the solvent at reduced pressure by rotator evaporation, the residue was subjected to column chromatography with a mixture of light petroleum and ethyl acetate (v/v = 5:1) as eluent to give the pure products for analysis.

1′-Benzyl-3,4-dimethyl-6-(4-methylbenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1a)

White solid, 86%, 0.187 g, mp 118–120 °C; 1H NMR (400 MHz, CDCl3) δ: 7.78–7.76 (m, 2H, ArH), 7.29–7.19 (m, 7H, ArH), 7.12 (d, J = 8.4 Hz, 1H, ArH), 6.98 (s, 1H, ArH), 6.93 (d, J = 8.4 Hz, 1H, ArH), 4.90 (d, J = 16.0 Hz, 1H, CH), 4.82 (d, J = 16.0 Hz, 1H, CH), 4.31–4.26 (m, 1H, CH), 2.89 (d, J = 16.8 Hz, 1H, CH), 2.57–2.49 (m, 2H, CH), 2.39 (s, 3H, CH3), 1.85–1.75 (m, 4H, CH, CH3), 1.70 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 199.6, 179.2, 143.9, 141.2, 135.5, 134.9, 129.2, 128.7, 128.6, 127.6, 127.4, 127.1, 127.0, 124.9, 124.1, 124.0, 109.8, 48.8, 47.5, 43.9, 41.5, 33.5, 21.6, 19.1, 18.6; IR (KBr) υ: 3029, 2931, 2841, 1695, 1608, 1484, 1435, 1283, 1173, 1075, 1024, 815, 743 cm–1; MS (m/z): HRMS (ESI) calcd for C30H30NO2 ([M + H]+): 436.2277. Found: 436.2293.

6-Benzoyl-1′-benzyl-5′-chloro-3,4-dimethylspiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1b)

White solid, 80%, 0.182 g, mp 112–114 °C; 1H NMR (400 MHz, CDCl3) δ: 7.87–7.85 (m, 2H, ArH), 7.55–7.52 (m, 1H, ArH), 7.44–7.41 (m, 2H, ArH), 7.30–7.25 (m, 2H, ArH), 7.22–7.20 (m, 3H, ArH), 7.13 (d, J = 8.0 Hz, 1H, ArH), 6.99 (s, 1H, ArH), 6.64 (d, J = 7.6 Hz, 1H, ArH), 4.90 (d, J = 15.6 Hz, 1H, CH), 4.82 (d, J = 16.0 Hz, 1H, CH), 4.33–4.29 (m, 1H, CH), 2.90 (d, J = 16.8 Hz, 1H, CH), 2.57–2.44 (m, 2H, CH), 1.86–1.80 (m, 4H, CH, CH3), 1.70 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 200.1, 179.2, 141.2, 136.2, 135.5, 134.8, 133.3, 132.9, 128.9, 128.7, 128.7, 128.4, 128.4, 128.3, 127.6, 127.4, 127.2, 127.0, 126.8, 124.9, 124.1, 123.9, 109.9, 48.7, 47.8, 43.9, 41.6, 33.3, 19.1, 18.6; IR (KBr) υ: 1700, 1604, 1485, 1433, 1288, 1173, 1075, 1027, 814, 745 cm–1; MS (m/z): HRMS (ESI) calcd for C29H26ClNNaO2 ([M + Na]+): 478.1550. Found: 478.1545.

1′-Benzyl-5′-chloro-3,4-dimethyl-6-(4-methylbenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1c)

White solid, 79%, 0.184 g, mp 132–134 °C; 1H NMR (400 MHz, CDCl3) δ: 7.78–7.76 (m, 2H, ArH), 7.29–7.19 (m, 7H, ArH), 7.12 (dd, J1 = 8.4 Hz, J1 = 2.0 Hz, 1H, ArH), 6.99–6.98 (m, 1H, ArH), 6.63 (d, J = 8.0 Hz, 1H, ArH), 4.90 (d, J = 16.0 Hz, 1H, CH), 4.82 (d, J = 15.6 Hz, 1H, CH), 4.29 (dd, J1 = 11.6 Hz, J1 = 6.8 Hz, 1H, CH), 2.89 (d, J = 16.8 Hz, 1H, CH), 2.57–2.49 (m, 2H, CH), 2.39 (s, 3H, CH3), 1.86–1.80 (m, 4H, CH, CH3), 1.70 (s, 3H, CH3); 13C NMR (150 MHz, CDCl3) δ: 199.7, 179.3, 144.0, 141.2, 135.5, 134.9, 133.6, 129.3, 128.7, 127.6, 127.4, 127.2, 127.0, 125.0, 124.1, 124.0, 109.8, 48.8, 47.6, 43.9, 41.5, 33.5, 21.6, 19.1, 18.7; IR (KBr) υ: 1708, 1698, 1608, 1482, 1435, 1285, 1171, 1075, 1023, 821, 743, 728 cm–1; MS (m/z): HRMS (ESI) calcd for C30H29ClNO2 ([M + H]+): 470.1887. Found: 470.1882.

1′-Butyl-5′-chloro-6-(4-methoxybenzoyl)-3,4-dimethylspiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1d)

White solid, 72%, 0.162 g, mp 109–111 °C; 1H NMR (400 MHz, CDCl3) δ: 7.84–7.82 (m, 2H, ArH), 7.26–7.23 (m, 1H, ArH), 7.01–7.00 (m, 1H, ArH), 6.89–6.87 (m, 2H, ArH), 6.80 (d, J = 8.4 Hz, 1H, ArH), 4.19 (dd, J1 = 12.0 Hz, J1 = 6.4 Hz, 1H, CH), 3.84 (s, 3H, OCH3), 3.70–3.63 (m, 1H, CH), 3.57–3.50 (m, 1H, CH), 2.82 (d, J = 16.4 Hz, 1H, CH), 2.55–2.44 (m, 2H, CH), 1.79–1.74 (m, 5H, CH, CH3), 1.69 (s, 3H, CH3), 1.55–1.43 (m, 2H, CH), 1.29–1.27 (m, 1H, CH), 2.55–2.44 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (150 MHz, CDCl3) δ: 198.3, 178.9, 163.5, 141.6, 135.1, 130.9, 129.2, 127.3, 127.2, 124.9, 124.2, 124.0, 113.6, 108.8, 55.4, 48.8, 47.0, 41.1, 39.9, 33.4, 29.2, 20.0, 19.0, 18.6, 13.7; IR (KBr) υ: 3021, 2930, 2844, 1705, 1605, 1487, 1441, 1286, 1178, 1105, 1029, 815, 743, 702 cm–1; MS (m/z): HRMS (ESI) calcd for C27H31ClNO3 ([M + H]+): 452.1992. Found: 452.1981.

1′-Benzyl-5′-fluoro-3,4-dimethyl-6-(4-methylbenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1e)

White solid, 78%, 0.177 g, mp 138–140 °C; 1H NMR (400 MHz, CDCl3) δ: 7.79–7.77 (m, 2H, ArH), 7.28–7.26 (m, 1H, ArH), 7.24–7.19 (m, 6H, ArH), 6.87–6.79 (m, 2H, ArH), 6.62 (dd, J1 = 8.4 Hz, J1 = 4.4 Hz, 1H, ArH), 4.90 (d, J = 15.6 Hz, 1H, CH), 4.81 (d, J = 16.0 Hz, 1H, CH), 4.31 (dd, J1 = 13.2 Hz, J1 = 8.8 Hz, 1H, CH), 2.91 (d, J = 16.4 Hz, 1H, CH), 2.55–2.44 (m, 2H, CH), 2.38 (s, 3H, CH3), 1.85–1.79 (m, 4H, CH, CH3), 1.69 (s, 3H, CH3); 13C NMR (150 MHz, CDCl3) δ: 199.8, 179.5, 159.1 (d, J = 237.0 Hz), 144.0, 138.5, 135.7, 134.8 (d, J = 8.3 Hz), 133.7, 129.3, 128.8, 128.7, 127.4, 127.1, 125.0, 124.1, 113.4 (d, J = 23.1 Hz), 112.0 (d, J = 25.4 Hz), 109.3 (d, J = 8.1 Hz), 49.0, 47.4, 44.0, 41.5, 33.5, 21.6, 19.1, 18.6; IR (KBr) υ: 3034, 2933, 2842, 1711, 1602, 1485, 1433, 1287, 1178, 1095, 1027, 815, 740 cm–1; MS (m/z): HRMS (ESI) calcd for C30H29FNO2 ([M + H]+): 454.2182. Found: 454.2179.

1′-Benzyl-5′-methyl-3,4-dimethyl-6-(4-methoxybenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1f)

White solid, 84%, 0.195 g, mp 124–126 °C; 1H NMR (400 MHz, CDCl3) δ: 7.90–7.88 (m, 2H, ArH), 7.25–7.17 (m, 5H, ArH), 6.95 (d, J = 7.2 Hz, 1H, ArH), 6.90–6.83 (m, 3H, ArH), 6.59 (d, J = 7.6 Hz, 1H, ArH), 4.88 (d, J = 16.0 Hz, 1H, CH), 4.75 (d, J = 16.0 Hz, 1H, CH), 4.26 (dd, J1 = 11.2 Hz, J1 = 8.8 Hz, 1H, CH), 3.84 (s, 3H, OCH3), 2.89 (d, J = 16.4 Hz, 1H, CH), 2.64–2.57 (m, 1H, CH), 2.47–2.43 (m, 1H, CH), 2.28 (s, 3H, CH3), 1.81 (s, 3H, CH3), 1.70 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 198.4, 179.5, 163.4, 140.1, 136.0, 133.1, 131.5, 130.9, 129.4, 128.5, 127.6, 127.1, 127.0, 124.8, 124.6, 124.1, 113.6, 108.6, 55.4, 48.9, 46.8, 43.8, 41.5, 33.6, 21.4, 19.0, 18.6; IR (KBr) υ: 3030, 2931, 2843, 1709, 1692, 1608, 1487, 1438, 1286, 1174, 1075, 1024, 817, 743 cm–1; MS (m/z): HRMS (ESI) calcd for C31H32NO3 ([M + H]+): 466.2382. Found: 466.2374.

1′-Benzyl-3,4-diphenyl-6-(4-methylbenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1g)

White solid, 81%, 0.226 g, mp 201–203 °C; 1H NMR (400 MHz, CDCl3) δ: 7.86–7.84 (m, 2H, ArH), 7.47 (d, J = 7.6 Hz, 1H, ArH), 7.25–7.19 (m, 8H, ArH), 7.18–7.14 (m, 2H, ArH), 7.12–7.08 (m, 6H, ArH), 7.07–7.05 (m, 1H, ArH), 6.98–6.96 (m, 2H, ArH), 6.78 (d, J = 7.6 Hz, 1H, ArH), 4.92 (d, J = 15.6 Hz, 1H, CH), 4.85 (d, J = 16.0 Hz, 1H, CH), 4.63–4.59 (m, 1H, CH), 3.44–3.38 (m, 1H, CH), 3.10–3.08 (m, 2H, CH), 2.42 (d, J = 17.6 Hz, 1H, CH), 2.39 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 199.2, 179.1, 143.9, 142.7, 141.9, 141.5, 135.8, 133.9, 133.7, 133.2, 132.7, 129.2, 128.8, 128.8, 128.6, 128.0, 127.9, 127.6, 127.3, 127.1, 126.6, 126.4, 123.6, 122.6, 109.3, 48.4, 47.2, 43.9, 42.2, 33.6, 21.6; IR (KBr) υ: 3035, 2929, 1701, 1602, 1483, 1428, 1350, 1291, 1023, 955, 870, 742, 700 cm–1; MS (m/z): HRMS (ESI) calcd for C40H34NO2 ([M + H]+): 560.2590. Found: 560.2611.

1′-Benzyl-5′-chloro-3,4-diphenyl-6-(4-methylbenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1h)

White solid, 79%, 0.234 g, mp 208–210 °C; 1H NMR (400 MHz, CDCl3) δ: 7.85–7.83 (m, 2H, ArH), 7.43 (d, J = 1.6 Hz, 1H, ArH), 7.29–7.24 (m, 5H, ArH), 7.22–7.19 (m, 3H, ArH), 7.17–7.13 (m, 2H, ArH), 7.12–7.08 (m, 6H, ArH), 6.98–6.96 (m, 2H, ArH), 6.69 (d, J = 8.0 Hz, 1H, ArH), 4.93 (d, J = 16.0 Hz, 1H, CH), 4.86 (d, J = 16.0 Hz, 1H, CH), 4.63–4.58 (m, 1H, CH), 3.40 (d, J = 17.6 Hz, 1H, CH), 3.16–3.10 (m, 1H, CH), 3.05–2.97 (m, 1H, CH), 2.43–2.39 (m, 4H, CH, CH3); 13C NMR (100 MHz, CDCl3) δ: 199.1, 178.8, 144.2, 141.6, 141.3, 141.2, 135.4, 134.5, 133.9, 133.6, 133.0, 129.3, 128.7, 128.7, 128.7, 128.7, 128.1, 128.0, 127.9, 127.5, 127.4, 127.0, 126.7, 126.6, 124.1, 110.1, 48.4, 47.5, 44.0, 42.1, 33.6, 21.6; IR (KBr) υ: 3051, 2925, 2838, 1709, 1680, 1602, 1482, 1434, 1370, 1338, 1284, 1222, 1186, 1110, 1073, 1023, 960, 912, 871, 810, 742 cm–1; MS (m/z): HRMS (ESI) calcd for C40H33ClNO2 ([M + H]+): 594.2200. Found: 594.2210.

6-Benzoyl-1′-benzyl-5′-chloro-3,4-diphenylspiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1i)

White solid, 85%, 0.246 g, mp 208–209 °C; 1H NMR (400 MHz, CDCl3) δ: 7.94–7.92 (m, 2H, ArH), 7.57–7.53 (m, 1H, ArH), 7.47–7.43 (m, 3H, ArH), 7.29–7.25 (m, 2H, ArH), 7.24–7.23 (m, 2H, ArH), 7.21–7.15 (m, 4H, ArH), 7.17–7.13 (m, 2H, ArH), 7.12–7.08 (m, 6H, ArH), 6.98–6.96 (m, 2H, ArH), 6.69 (d, J = 8.0 Hz, 1H, ArH), 4.93 (d, J = 16.0 Hz, 1H, CH), 4.86 (d, J = 16.0 Hz, 1H, CH), 4.65–4.61 (m, 1H, CH), 3.41 (d, J = 17.2 Hz, 1H, CH), 3.17–3.11 (m, 1H, CH), 3.06–2.97 (m, 1H, CH), 2.41 (d, J = 17.2 Hz, 1H, CH); 13C NMR (100 MHz, CDCl3) δ: 199.6, 178.7, 141.6, 141.3, 141.2, 136.1, 135.3, 134.4, 133.8, 133.2, 133.0, 128.7, 128.7, 128.7, 128.6, 128.5, 128.1, 127.9, 127.9, 127.5, 127.0, 126.7, 126.6, 124.1, 110.1, 48.4, 47.6, 44.0, 42.1, 33.4; IR (KBr) υ: 3032, 2938, 1693, 1605, 1484, 1431, 1345, 1283, 1175, 1074, 1024, 958, 910, 872, 811, 742 cm–1; MS (m/z): HRMS (ESI) calcd for C39H31ClNO2 ([M + H]+): 580.2043. Found: 580.2062.

1′-Benzyl-5′-chloro-3,4-diphenyl-6-(4-chlorobenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1j)

White solid, 77%, 0.236 g, mp 199–200 °C; 1H NMR (400 MHz, CDCl3) δ: 7.88–7.86 (m, 2H, ArH), 7.43–7.41 (m, 3H, ArH), 7.29–7.27 (m, 1H, ArH), 7.25–7.23 (m, 2H, ArH), 7.21–7.18 (m, 4H, ArH), 7.16–7.06 (m, 7H, ArH), 6.98–6.96 (m, 2H, ArH), 6.70 (d, J = 8.0 Hz, 1H, ArH), 4.92 (d, J = 16.0 Hz, 1H, CH), 4.84 (d, J = 15.6 Hz, 1H, CH), 4.59–4.55 (m, 1H, CH), 3.41–3.36 (m, 1H, CH), 3.12–2.97 (m, 2H, CH), 2.42 (d, J = 17.2 Hz, 1H, CH); 13C NMR (100 MHz, CDCl3) δ: 198.4, 178.6, 141.5, 141.3, 141.1, 139.8, 135.2, 134.4, 134.1, 133.6, 133.0, 130.0, 129.0, 128.7, 128.6, 128.1, 128.0, 128.0, 127.6, 127.5, 127.0, 126.8, 126.6, 124.2, 110.1, 48.5, 47.4, 44.1, 41.9, 33.3; IR (KBr) υ: 3045, 2933, 1697, 1604, 1489, 1434, 1371, 1284, 1175, 1089, 1026, 949, 815, 741, 695 cm–1; MS (m/z): HRMS (ESI) calcd for C39H30Cl2NO2 ([M + H]+): 614.1654. Found: 614.1664.

1′-Benzyl-5′-methyl-3,4-diphenyl-6-(4-chlorobenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1k)

White solid, 73%, 0.216 g, mp 197–199 °C; 1H NMR (400 MHz, CDCl3) δ: 7.89–7.87 (m, 2H, ArH), 7.41–7.39 (m, 2H, ArH), 7.31 (s, 1H, ArH), 7.25–7.16 (m, 7H, ArH), 7.13–7.02 (m, 7H, ArH), 6.98–6.96 (m, 2H, ArH), 6.68–6.66 (m, 1H, ArH), 4.89 (d, J = 16.0 Hz, 1H, CH), 4.80 (d, J = 16.0 Hz, 1H, CH), 4.59–4.54 (m, 1H, CH), 3.40 (d, J = 17.2 Hz, 1H, CH), 3.15–3.00 (m, 2H, CH), 2.43 (d, J = 17.6 Hz, 1H, CH), 2.34 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 198.5, 178.8, 141.8, 141.5, 140.2, 139.6, 135.8, 134.7, 133.5, 133.3, 132.4, 131.9, 130.1, 128.9, 128.8, 128.7, 128.6, 128.1, 128.1, 127.9, 127.3, 127.0, 126.7, 126.5, 124.7, 109.0, 48.5, 47.1, 43.9, 42.1, 33.3, 21.5; IR (KBr) υ: 3027, 2984, 2919, 1722, 1608, 1483, 1428, 1352, 1276, 1209, 1110, 1027, 944, 869, 817, 744, 705 cm–1; MS (m/z): HRMS (ESI) calcd for C40H33ClNO2 ([M + H]+): 594.2200. Found: 594.2218.

1′-Butyl-5′-chloro-3,4-diphenyl-6-(4-methoxybenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1l)

White solid, 80%, 0.230 g, mp 207–209 °C; 1H NMR (400 MHz, CDCl3) δ: 7.92–7.90 (m, 2H, ArH), 7.43 (d, J = 2.0 Hz, 1H, ArH), 7.30 (dd, J1 = 8.4 Hz, J2 = 2.0 Hz, 1H, ArH), 7.19–7.16 (m, 2H, ArH), 7.14–7.07 (m, 6H, ArH), 6.98–6.96 (m, 2H, ArH), 6.91–6.89 (m, 2H, ArH), 6.85 (d, J = 8.4 Hz, 1H, ArH), 4.53–4.48 (m, 1H, CH), 3.85 (s, 3H, OCH3), 3.73–3.66 (m, 1H, CH), 3.61–3.54 (m, 1H, CH), 3.35–3.30 (m, 1H, CH), 3.06–3.04 (m, 2H, CH), 2.34 (d, J = 17.6 Hz, 1H, CH), 1.57–1.46 (m, 2H, CH), 1.29–1.23 (m, 2H, CH), 0.86 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 197.7, 178.4, 163.6, 141.7, 141.6, 141.3, 134.7, 133.9, 132.9, 130.9, 129.2, 128.7, 128.7, 128.1, 127.9, 127.5, 127.4, 126.6, 126.5, 124.2, 113.7, 109.1, 55.4, 48.4, 46.9, 41.6, 40.0, 33.5, 29.2, 20.0, 13.6; IR (KBr) υ: 3069, 2959, 2926, 1706, 1666, 1600, 1484, 1428, 1356, 1314, 1262, 1218, 1175, 1115, 1024, 951, 916, 849, 817, 743, 701 cm–1; MS (m/z): HRMS (ESI) calcd for C37H35ClNO3 ([M + H]+): 576.2305. Found: 576.2324.

1′-Benzyl-5′-fluoro-3,4-(bis-4-methylphenyl)-6-(4-methylbenzoyl)spiro[cyclohexane-1,3′-indolin]-3-en-2′-one (1m)

White solid, 83%, 0.251 g, mp 170–172 °C; 1H NMR (400 MHz, CDCl3) δ: 7.85–7.83 (m, 2H, ArH), 7.28–7.26 (m, 1H, ArH), 7.25–7.24 (m, 2H, ArH), 7.23–7.16 (m, 5H, ArH), 7.00–6.96 (m, 4H, ArH), 6.94–6.89 (m, 3H, ArH), 6.87–6.85 (m, 2H, ArH), 6.66 (dd, J1 = 8.4 Hz, J2 = 4.4 Hz, 1H, ArH), 4.91 (d, J = 16.0 Hz, 1H, CH), 4.85 (d, J = 16.0 Hz, 1H, CH), 4.61–4.57 (m, 1H, CH), 3.38 (d, J = 17.2 Hz, 1H, CH), 3.12–3.06 (m, 1H, CH), 3.02–2.98 (m, 1H, CH), 2.39–2.35 (m, 4H, CH, CH3), 2.25 (s, 3H, CH3), 2.23 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 199.3, 179.0, 159.2 (d, J = 238.0 Hz), 144.1, 138.9, 138.7, 138.6, 138.4, 136.3, 136.1, 135.5, 134.5 (d, J = 8.4 Hz), 133.7, 133.1, 132.3, 129.3, 128.8, 128.7, 128.7, 128.6, 128.6, 127.4, 127.0, 113.6 (d, J = 23.2 Hz), 112.0 (d, J = 25.5 Hz), 109.5 (d, J = 8.3 Hz), 48.7, 48.7, 47.4, 44.0, 42.2, 33.6, 21.6, 21.0; IR (KBr) υ: 3027, 2960, 2926, 2872, 1708, 1608, 1495, 1437, 1360, 1293, 1195, 1107, 1035, 853, 816, 745 cm–1; MS (m/z): HRMS (ESI) calcd for C42H37FNO2 ([M + H]+): 606.2808. Found: 606.2834.

Ethyl 1′-benzyl-3,4-(bis-4-methylphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2a)

White solid, 69%, 0.186 g, mp 151–153 °C; 1H NMR (400 MHz, CDCl3) δ: 7.30 (d, J = 7.2 Hz, 1H, ArH), 7.27–7.25 (m, 2H, ArH), 7.22–7.18 (m, 2H, ArH), 7.15–7.11 (m, 1H, ArH), 7.09–7.05 (m, 1H, ArH), 6.96–6.94 (m, 2H, ArH), 6.92–6.89 (m, 3H, ArH), 6.79–6.77 (m, 2H, ArH), 6.73–6.71 (m, 2H, ArH), 6.68 (d, J = 7.6 Hz, 1H, ArH), 5.01 (d, J = 16.0 Hz, 1H, CH), 4.77 (d, J = 15.6 Hz, 1H, ArH), 3.86–3.75 (m, 2H, CH), 3.56 (dd, J1 = 11.2 Hz, J2 = 6.8 Hz, 1H, CH), 3.17 (d, J = 16.8 Hz, 1H, CH), 3.13–2.94 (m, 2H, CH), 2.27–2.23 (m, 1H, CH), 2.16 (s, 3H, CH3), 2.09 (s, 3H, CH3), 0.87 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 179.6, 171.6, 143.0, 139.1, 138.8, 136.1, 136.1, 135.9, 132.8, 132.1, 131.8, 128.8, 128.7, 128.6, 127.9, 127.5, 127.3, 123.8, 122.5, 109.1, 60.6, 48.0, 44.6, 44.1, 42.2, 32.0, 21.1, 21.1, 13.9; IR (KBr) υ: 3024, 2981, 2919, 1720, 1610, 1483, 1428, 1352, 1273, 1207, 1107, 1029, 944, 868, 818, 744 cm–1; MS (m/z): HRMS (ESI) calcd for C37H36NO3 ([M + H]+): 546.2695. Found: 542.2692.

Ethyl 1′-butyl-5′-fluoro-3,4-(bis-4-methylphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2b)

White solid, 82%, 0.215 g, mp 163–165 °C; 1H NMR (400 MHz, CDCl3) δ: 7.12 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz, 1H, ArH), 7.04–7.01 (m, 4H, ArH), 6.99 (dd, J1 = 8.8 Hz, J2 = 2.4 Hz, 1H, ArH), 6.90–6.88 (m, 2H, ArH), 6.83–6.79 (m, 3H, ArH), 3.98–3.89 (m, 2H, CH), 3.83–3.76 (m, 1H, CH), 3.73–3.64 (m, 1H, CH), 3.58 (d, J1 = 11.6 Hz, J2 = 6.4 Hz, 1H, CH), 3.19–3.13 (m, 2H, CH), 3.02–2.94 (m, 1H, CH), 2.28–2.23 (m, 4H, CH, CH3), 2.21 (s, 3H, CH3), 1.71–1.64 (m, 2H, CH), 1.45–1.36 (m, 2H, CH), 1.05 (t, J = 7.2 Hz, 3H, CH3), 0.96 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 179.0, 171.4, 160.0, 158.9 (d, J = 238.1 Hz), 139.4 (d, J = 1.7 Hz), 138.8, 138.6, 136.2, 135.9, 133.5 (d, J = 8.1 Hz), 132.7, 131.9, 128.8, 128.6, 128.6, 128.6, 113.9 (d, J = 23.2 Hz), 112.2 (d, J = 25.0 Hz), 108.5 (d, J = 8.1 Hz), 60.6, 48.1, 44.5, 41.7, 40.1, 31.9, 29.3, 21.1, 21.0, 20.1, 13.9, 13.7; IR (KBr) υ: 3024, 2987, 2923, 1707, 1608, 1477, 1433, 1352, 1274, 1213, 1108, 1027, 943, 865, 817, 743, 702 cm–1; MS (m/z): HRMS (ESI) calcd for C34H37FNO3 ([M + H]+): 526.2757. Found: 526.2754.

Ethyl 1′-benzyl-5′-chloro-3,4-(bis-4-methylphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2c)

White solid, 76%, 0.218 g, mp 154–155 °C; 1H NMR (400 MHz, CDCl3) δ: 7.35–7.34 (m, 1H, ArH), 7.32–7.28 (m, 4H, ArH), 7.27–7.25 (m, 1H, ArH), 7.15 (dd, J1 = 8.4 Hz, J2 = 2.0 Hz, 1H, ArH), 7.05–7.01 (m, 4H, ArH), 6.92–6.90 (m, 2H, ArH), 6.83–6.81 (m, 2H, ArH), 6.67 (d, J = 8.4 Hz, 1H, ArH), 5.08 (d, J = 15.6 Hz, 1H, CH), 4.85 (d, J = 15.6 Hz, 1H, CH), 4.02–3.95 (m, 1H, CH), 3.94–3.88 (m, 1H, CH), 3.67–3.63 (m, 1H, CH), 3.62–3.18 (m, 2H, CH), 2.34–2.28 (m, 4H, CH, CH3), 2.22 (s, 3H, CH3), 1.04 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 179.2, 171.4, 141.7, 138.7, 138.5, 136.2, 136.0, 135.6, 133.5, 133.0, 131.8, 128.8, 128.7, 128.6, 128.6, 127.7, 127.6, 127.2, 124.3, 109.9, 60.8, 48.1, 44.6, 44.2, 42.0, 32.0, 21.1, 21.0, 13.9; IR (KBr) υ: 3048, 2981, 2919, 2846, 1710, 1609, 1592, 1437, 1356, 1273, 1195, 1113, 1031, 866, 818, 741 cm–1; MS (m/z): HRMS (ESI) calcd for C37H35ClNO3 ([M + H]+): 576.2305. Found: 576.2331.

Ethyl 1′-butyl-5′-methyl-3,4-(bis-4-methylphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2d)

White solid, 75%, 0.195 g, mp 150–152 °C; 1H NMR (400 MHz, CDCl3) δ: 7.19 (s, 1H, ArH), 7.08 (d, J = 8.0 Hz, 1H, ArH), 7.04–7.00 (m, 4H, ArH), 6.89–6.87 (m, 2H, ArH), 6.81–6.78 (m, 3H, CH), 3.96–3.87 (m, 2H, CH), 3.83–3.76 (m, 1H, CH), 3.71–3.64 (m, 1H, CH), 3.57–3.53 (m, 1H, CH), 3.17–3.00 (m, 3H, CH), 2.31–2.23 (m, 7H, CH, 2CH3), 2.20 (s, 3H, CH3), 1.72–1.64 (m, 2H, CH), 1.45–1.36 (m, 2H, CH), 1.02 (t, J = 7.2 Hz, 3H, CH3), 0.95 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 179.2, 171.6, 140.9, 139.1, 139.0, 136.0, 135.7, 132.7, 132.2, 132.0, 131.3, 128.7, 128.7, 128.5, 128.0, 124.9, 107.9, 60.4, 47.8, 44.5, 41.9, 40.0, 32.0, 29.4, 21.4, 21.1, 21.0, 20.2, 13.9, 13.7; IR (KBr) υ: 3033, 2972, 2921, 2876, 1712, 1607, 1486, 1436, 1372, 1282, 1193, 1111, 1025, 862, 816, 742, 700 cm–1; MS (m/z): HRMS (ESI) calcd for C35H40NO3 ([M + H]+): 522.3008. Found: 522.3031.

Ethyl 1′-benzyl-5′-chloro-3,4-(diphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2e)

White solid, 83%, 0.227 g, mp 154–156 °C; 1H NMR (400 MHz, CDCl3) δ: 7.38 (s, 1H, ArH), 7.33–7.29 (m, 4H, ArH), 7.25–7.22 (m, 1H, ArH), 7.20–7.18 (m, 2H, ArH), 7.14–7.12 (m, 3H, ArH), 7.10–7.05 (m, 3H, ArH), 6.93–6.90 (m, 2H, ArH), 6.69 (d, J = 8.0 Hz, 1H, ArH), 5.08 (d, J = 15.6 Hz, 1H, CH), 4.87 (d, J = 15.6 Hz, 1H, ArH), 4.00–3.89 (m, 2H, CH), 3.68 (dd, J1 = 11.6 Hz, J2 = 6.8 Hz, 1H, CH), 3.30–3.21 (m, 2H, CH), 3.09–3.02 (m, 1H, CH), 2.36 (d, J = 17.2 Hz, 1H, CH), 1.04 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 179.1, 171.4, 141.7, 141.5, 141.4, 135.5, 133.6, 133.5, 132.5, 128.8, 128.8, 128.1, 127.9, 127.8, 127.8, 127.6, 127.2, 126.7, 126.5, 124.3, 110.0, 60.8, 48.0, 44.6, 44.2, 41.9, 31.9, 13.9; IR (KBr) υ: 3029, 2985, 2921, 1712, 1607, 1483, 1429, 1352, 1276, 1209, 1110, 1025, 947, 869, 825, 741 cm–1; MS (m/z): HRMS (ESI) calcd for C35H31ClNO3 ([M + H]+): 548.1992. Found: 548.1979.

Ethyl 5′-chloro-3,4-(diphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2f)

White solid, 77%, 0.175 g, mp 145–147 °C; 1H NMR (400 MHz, CDCl3) δ: 8.31 (s, 1H, NH), 7.35 (s, 1H, ArH), 7.26–7.21 (m, 3H, ArH), 7.17–7.12 (m, 4H, ArH), 7.09–7.04 (m, 3H, ArH), 6.92–6.89 (m, 3H, ArH), 4.05–3.95 (m, 2H, CH), 3.62–3.57 (m, 1H, CH), 3.26–3.17 (m, 2H, CH), 3.06–2.99 (m, 1H, CH), 2.40 (d, J = 18.0 Hz, 1H, CH), 1.10 (t, J = 7.2 Hz, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 181.4, 171.4, 141.3, 139.7, 133.8, 133.5, 132.3, 128.8, 128.1, 128.0, 127.9, 127.6, 126.7, 126.5, 124.5, 110.8, 61.0, 48.7, 44.5, 41.5, 31.6, 13.8; IR (KBr) υ: 1715, 1605, 1486, 1431, 1355, 1277, 1211, 1109, 1027, 945, 869, 841, 745 cm–1; MS (m/z): HRMS (ESI) calcd for C28H24ClNNaO3 ([M + Na]+): 480.1342. Found: 480.1331.

Ethyl 3,4-(bis-4-methylphenyl)-2′-oxospiro[cyclohexane-1,3′-indolin]-3-ene-6-carboxylate (2g)

White solid, 80%, 0.180 g, mp 160–162 °C; 1H NMR (400 MHz, CDCl3) δ: 8.03 (s, 1H, NH), 7.36–7.35 (m, 1H, ArH), 7.26–7.22 (m, 1H, ArH), 7.02 (brs, 5H, ArH), 6.95–6.93 (m, 1H, ArH), 6.88–6.87 (m, 2H, ArH), 6.81–6.79 (m, 2H, ArH), 3.98–3.93 (m, 2H, CH), 3.56–3.54 (m, 1H, CH), 3.18–3.14 (m, 2H, CH), 3.07–2.99 (m, 1H, CH), 2.37 (d, J = 16.4 Hz, 1H, CH), 2.28 (s, 3H, CH3), 2.20 (s, 3H, CH3), 1.05 (brs, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 181.8, 171.6, 141.1, 138.9, 138.8, 136.0, 135.8, 132.7, 132.1, 131.9, 128.7, 128.7, 128.5, 128.0, 124.1, 122.4, 109.9, 60.7, 48.6, 44.5, 41.8, 31.7, 21.1, 21.0, 13.8; IR (KBr) υ: 3033, 2987, 2923, 1711, 1609, 1487, 1434, 1354, 1278, 1215, 1116, 1032, 948, 869, 817, 747, 710 cm–1; MS (m/z): HRMS (ESI) calcd for C30H29NNaO3 ([M + Na]+): 474.2045. Found: 474.2035.

6-Phenyl-3,4-(bis-p-methyl-phenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3a)

White solid, 54%, 0.126 g, mp 197–199 °C; 1H NMR (400 MHz, CDCl3) δ: 7.86 (d, J = 7.2 Hz, 1H, ArH), 7.70–7.66 (m, 2H, ArH), 7.62–7.59 (m, 1H, ArH), 7.10–7.08 (m, 2H, ArH), 7.05–7.00 (m, 4H, ArH), 6.96–6.94 (m, 6H, ArH), 3.73–3.69 (m, 1H, CH), 3.56–3.48 (m, 1H, CH), 3.16 (d, J = 17.6 Hz, 1H, CH), 2.79–2.74 (m, 1H, CH), 2.50 (d, J = 18.0 Hz, 1H, CH), 2.25–2.20 (m, 6H, 2CH3); 13C NMR (100 MHz, CDCl3) δ: 203.5, 202.7, 142.2, 141.2, 139.6, 139.3, 135.5, 135.5, 135.4, 135.1, 134.7, 129.9, 128.9, 128.8, 128.5, 128.4, 128.3, 128.3, 128.3, 128.1, 127.0, 122.8, 122.6, 57.2, 45.3, 37.6, 36.0, 21.0; IR (KBr) υ: 1738, 1703, 1594, 1504, 1453, 1342, 1244, 1103, 1034, 946, 816, 759 cm–1; MS (m/z): HRMS (ESI) calcd for C34H28NaO2 ([M + Na]+): 491.1987. Found: 491.1991.

6-(p-Methylphenyl)-3,4-(bis-4-methylphenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3b)

White solid, 58%, 0.140 g, mp 211–213 °C; 1H NMR (400 MHz, CDCl3) δ: 7.87 (d, J = 6.4 Hz, 1H, ArH), 7.69–7.68 (m, 2H, ArH), 7.63 (d, J = 6.4 Hz, 1H, ArH), 7.04–7.03 (m, 2H, ArH), 6.96–6.92 (m, 8H, ArH), 6.83–6.81 (m, 2H, ArH), 3.53–3.46 (m, 1H, CH), 3.14 (d, J = 17.6 Hz, 1H, CH), 2.74 (d, J = 16.8 Hz, 1H, CH), 2.49 (d, J = 18.0 Hz, 1H, CH), 2.24–2.22 (s, 6H, 2CH3), 2.10 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 203.6, 202.8, 142.1, 141.3, 139.6, 139.3, 136.6, 136.4, 135.4, 135.4, 135.0, 134.9, 129.9, 128.9, 128.8, 128.4, 128.4, 128.1, 122.8, 122.6, 57.2, 44.8, 37.8, 36.2, 21.0, 21.0, 20.8; IR (KBr) υ: 1737, 1703, 1594, 1509, 1432, 1347, 1243, 1108, 1036, 953, 912, 814 cm–1; MS (m/z): HRMS (ESI) calcd for C35H30NaO2 ([M + Na]+): 505.2143. Found: 505.2149.

6-(p-Methoxyphenyl)-3,4-(diphenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3c)

White solid, 62%, 0.146 g, mp 216–218 °C; 1H NMR (400 MHz, CDCl3) δ: 7.87 (d, J = 7.6 Hz, 1H, ArH), 7.70–7.68 (m, 2H, ArH), 7.65–7.61 (m, 1H, ArH), 7.14–7.13 (m, 4H, ArH), 7.09–7.01 (m, 8H, ArH), 6.56 (d, J = 8.4 Hz, 1H, ArH), 3.69 (dd, J1 = 8.0 Hz, J2 = 4.4 Hz, 1H, CH), 3.62 (s, 3H, OCH3), 3.55–3.48 (m, 1H, CH), 3.18 (d, J = 18.0 Hz, 1H, CH), 2.76 (dd, J1 = 18.0 Hz, J2 = 4.0 Hz, 1H, CH), 2.52 (d, J = 18.0 Hz, 1H, CH); 13C NMR (100 MHz, CDCl3) δ: 203.6, 202.9, 158.3, 142.4, 142.1, 142.1, 141.3, 135.4, 135.2, 131.5, 130.5, 129.3, 129.0, 129.0, 127.7, 127.6, 126.1, 126.0, 122.8, 122.6, 113.5, 57.2, 55.0, 44.3, 37.5, 36.1; IR (KBr) υ: 1735, 1701, 1598, 1508, 1433, 1347, 1253, 1175, 1117, 1073, 1031, 954, 877, 831, 799, 764 cm–1; MS (m/z): HRMS (ESI) calcd for C33H26NaO3 ([M + Na]+): 493.1780. Found: 493.1786.

6-(p-Nitrophenyl)-3,4-(diphenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3d)

White solid, 52%, 0.126 g, mp 242–244 °C; 1H NMR (400 MHz, CDCl3) δ: 7.93–7.91 (m, 3H, ArH), 7.78–7.74 (m, 1H, ArH), 7.73–7.69 (m, 2H, ArH), 7.33–7.31 (m, 2H, ArH), 7.18–7.13 (m, 4H, ArH), 7.11–7.08 (m, 3H, ArH), 7.06–7.02 (m, 3H, ArH), 3.88 (dd, J1 = 12.0 Hz, J2 = 5.2 Hz, 1H, CH), 3.19 (d, J = 18.0 Hz, 1H, CH), 2.82 (dd, J1 = 17.6 Hz, J2 = 5.2 Hz, 1H, CH), 2.57 (d, J = 18.0 Hz, 1H, CH); 13C NMR (100 MHz, CDCl3) δ: 202.6, 201.9, 147.4, 146.9, 141.9, 141.7, 141.6, 140.8, 136.1, 135.7, 134.8, 130.6, 129.3, 128.9, 128.9, 127.8, 126.3, 123.4, 123.1, 123.0, 56.6, 44.6, 37.8, 35.5; IR (KBr) υ: 1739, 1701, 1594, 1514, 1430, 1341, 1247, 1172, 1107, 1016, 954, 851, 799, 759 cm–1; MS (m/z): HRMS (ESI) calcd for C32H23NNaO4 ([M + Na]+): 508.1525. Found: 508.1531.

6-(p-Nitro-phenyl)-3,4-(bis-p-methyl-phenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3e)

White solid, 59%, 0.151 g, mp 247–249 °C; 1H NMR (400 MHz, CDCl3) δ: 7.93–7.89 (m, 3H, ArH), 7.77–7.73 (m, 1H, ArH), 7.72–7.68 (m, 2H, ArH), 7.32–7.29 (m, 2H, ArH), 7.05–7.03 (m, 2H, ArH), 6.98–6.96 (m, 2H, ArH), 6.92 (brs, 4H, ArH), 3.85 (dd, J1 = 12.0 Hz, J2 = 5.2 Hz, 1H, CH), 3.60–3.52 (m, 1H, CH), 3.15 (d, J = 18.0 Hz, 1H, CH), 2.78 (dd, J1 = 17.6 Hz, J2 = 5.2 Hz, 1H, CH), 2.54 (d, J = 18.0 Hz, 1H, CH), 2.26 (s, 3H, CH3), 2.22 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 202.7, 201.8, 147.5, 146.9, 141.7, 140.8, 139.1, 138.8, 136.0, 135.8, 135.8, 135.7, 134.2, 130.0, 129.3, 128.8, 128.7, 128.5, 123.4, 123.1, 123.0, 56.7, 44.6, 38.0, 35.6, 21.0, 21.0; IR (KBr) υ: 1741, 1701, 1599, 1518, 1431, 1345, 1244, 1175, 1108, 1028, 957, 908, 817 cm–1; MS (m/z): HRMS (ESI) calcd for C34H27NNaO3 ([M + Na]+): 536.1838. Found: 536.1837.

6-(p-Bromo-phenyl)-3,4-(diphenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3f)

White solid, 48%, 0.124 g, mp 209–211 °C; 1H NMR (400 MHz, CDCl3) δ: 7.89 (d, J = 7.6 Hz, 1H, ArH), 7.76–7.68 (m, 3H, ArH), 7.18–7.13 (m, 6H, ArH), 7.10–7.04 (m, 5H, ArH), 7.02–6.99 (m, 3H, ArH), 3.71 (dd, J1 = 8.4 Hz, J2 = 4.8 Hz, 1H, CH), 3.56–3.48 (m, 1H, CH), 3.17 (d, J = 18.8 Hz, 1H, CH), 2.77 (dd, J1 = 17.6 Hz, J2 = 4.4 Hz, 1H, CH), 2.53 (d, J = 18.0 Hz, 1H, CH); 13C NMR (100 MHz, CDCl3) δ: 203.1, 202.4, 142.2, 141.9, 141.9, 141.1, 138.7, 135.7, 135.4, 135.2, 131.3, 130.5, 130.0, 129.0, 128.9, 127.7, 127.7, 126.2, 126.2, 123.0, 122.8, 121.0, 56.8, 44.4, 37.7, 35.8; IR (KBr) υ: 1737, 1702, 1591, 1486, 1415, 1345, 1245, 1165, 1073, 1004, 957, 876, 828, 797, 763 cm–1; MS (m/z): HRMS (ESI) calcd for C32H23BrNaO2 ([M + Na]+): 541.0779. Found: 541.0787.

6-(m-Chloro-phenyl)-3,4-(bis-4-methylphenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3g)

White solid, 56%, 0.140 g, mp 183–185 °C; 1H NMR (400 MHz, CDCl3) δ: 7.96 (d, J = 7.6 Hz, 1H, ArH), 7.78–7.75 (m, 2H, ArH), 7.70–7.67 (m, 1H, ArH), 7.25–7.23 (m, 1H, ArH), 7.12 (d, J = 7.6 Hz, 1H, ArH), 7.05–7.03 (m, 2H, ArH), 6.96–6.90 (m, 7H, ArH), 6.89–6.86 (m, 1H, ArH), 4.42 (dd, J1 = 10.8 Hz, J2 = 5.6 Hz, 1H, CH), 3.30–3.23 (m, 1H, CH), 3.15 (d, J = 18.4 Hz, 1H, CH), 2.81 (dd, J1 = 17.6 Hz, J2 = 5.2 Hz, 1H, CH), 2.54 (d, J = 18.0 Hz, 1H, CH), 2.24 (s, 3H, CH3), 2.20 (s, 3H, CH3); 13C NMR (100 MHz, CDCl3) δ: 202.7, 202.0, 142.1, 141.1, 139.3, 139.2, 138.0, 135.6, 135.5, 135.3, 134.9, 134.2, 130.0, 129.9, 128.8, 128.7, 128.5, 128.4, 128.0, 127.9, 126.7, 123.1, 122.9, 56.1, 40.1, 38.2, 36.9, 21.0, 21.0; IR (KBr) υ: 1739, 1703, 1594, 1509, 1433, 1347, 1243, 1108, 1036, 952, 815, 728 cm–1; MS (m/z): HRMS (ESI) calcd for C34H27ClNaO2 ([M + Na]+): 525.1597. Found: 525.1599.

6-(o-Chloro-phenyl)-3,4-(bis-p-methyl-phenyl)-spiro[cyclohexane-1,2′-inden]-3-ene-1′,3′-dione (3h)

White solid, 51%, 0.128 g, mp 159–161 °C; 1H NMR (400 MHz, CDCl3) δ: 7.96 (d, J = 7.6 Hz, 1H, ArH), 7.78–7.75 (m, 2H, ArH), 7.71–7.67 (m, 1H, ArH), 7.25–7.23 (m, 1H, ArH), 7.12 (d, J = 7.6 Hz, 1H, ArH), 7.04 (d, J = 7.6 Hz, 1H, ArH), 6.96–6.86 (m, 8H, ArH), 4.44–4.40 (m, 1H, CH), 3.30–3.23 (m, 1H, CH), 3.15 (d, J = 17.6 Hz, 1H, CH), 2.81 (dd, J1 = 17.6 Hz, J2 = 4.8 Hz, 1H, CH), 2.54 (d, J = 18.0 Hz, 1H, CH), 2.25–2.22 (m, 6H, 2CH3); 13C NMR (100 MHz, CDCl3) δ: 202.7, 202.0, 142.1, 141.1, 139.3, 139.2, 138.0, 135.6, 135.5, 135.3, 134.9, 134.2, 130.0, 129.9, 128.8, 128.8, 128.5, 128.4, 128.0, 127.9, 126.7, 123.1, 122.9, 56.1, 40.1, 38.2, 36.9, 21.0, 21.0; IR (KBr) υ: 1738, 1703, 1594, 1509, 1469, 1433, 1351, 1243, 1104, 1037, 954, 815, 753 cm–1; MS (m/z): HRMS (ESI) calcd for C34H27ClNaO2 ([M + Na]+): 525.1597. Found: 525.1603.