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Article

Regio- and Stereoselective Synthesis of a New Series of Spirooxindole Pyrrolidine Grafted Thiochromene Scaffolds as Potential Anticancer Agents

by
Assem Barakat
1,2,*,
Mohammad Shahidul Islam
1,
M. Ali
1,
Abdullah Mohammed Al-Majid
1,
Saeed Alshahrani
1,
Abdullah Saleh Alamary
1,
Sammer Yousuf
3 and
M. Iqbal Choudhary
3
1
Department of Chemistry, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
2
Department of Chemistry, Faculty of Science, Alexandria University, P.O. Box 426 Ibrahimia, Alexandria 21321, Egypt
3
H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
*
Author to whom correspondence should be addressed.
Symmetry 2021, 13(8), 1426; https://doi.org/10.3390/sym13081426
Submission received: 25 June 2021 / Revised: 27 July 2021 / Accepted: 28 July 2021 / Published: 4 August 2021
(This article belongs to the Special Issue Synthesis of Novel Anticancer Agents, Antivirals and Small Biological Molecules)
Browse Figures
Versions Notes

Abstract

:
A series of new spiro-heterocycles engrafted spirooxindole/pyrrolidine/thiochromene scaffolds was synthesized by the three-component 1,3-dipolar cycloaddition reactions in a fully controlled regio- and stereo-selective fashion. Condensation of several substituted isatin derivatives with L-proline generated the azomethine ylides which subsequently reacted with chalcones based thiochromene scaffold, and finally afforded the target spiro-compounds. This simple protocol furnished a structurally complex, biologically relevant spiro-heterocycles in good yields through a one-pot process. All synthesized chalcone-based thiochromene, along with the spirooxindole/pyrrolidine/thiochromene scaffolds, were tested for their anticancer activity against four cancer cell lines (PC3, HeLa, MCF-7, and MDA-MB231). Toxicity of these compounds was also evaluated against human fibroblast BJ cell line, and they appeared to be not cytotoxic. For the prostate cancer (PC3) cell line, the most active hybrid, among synthesized series, was compound (7f, IC50 = 8.7 ± 0.7 µM). The most potent spirooxindole/pyrrolidine/thiochromene hybrid against cervical (HeLa) cancer cells was compound (7k, IC50 = 8.4 ± 0.5 µM) having chlorine and p-trifluoromethyl substituents attached to phenyl rings. Finally, against the MCF-7 and MDA-MB231 breast cancer cell lines, compound (7d) was the most active member of this series (IC50 = 7.36 ± 0.37, and 9.44 ± 0.32 µM, respectively).

Graphical Abstract

1. Introductiong

The three-component 1,3-dipolar cycloaddition reaction is a powerful methodology for robust synthesis of structurally complex and biologically active spiro-heterocycles [1]. This method has been widely used for the synthesis of many compounds, engrafted spiro-centers, with diverse biological activities, and suitability to the integral structure rigidity. Spirooxindole/pyrrolidine heterocycles are ubiquitous in many natural products, such as tryprostatins A and B [2,3], formosanine [4], coerulescine [5], elacomine [6], horsfiline [7], pteropodine, isopteropodine [8], alstonisine [9], rychno-phyilline [10], strychnofoline [11], and other many alkaloids (Figure 1). These spiro-heterocycles with oxindole and pyrrolidine scaffolds possesses wide spectrum pharmacological activities, such as antimycobacterial [12,13], antimicrobial [14], local anesthetic [15], and anticancer [16,17,18,19,20,21,22,23] agents, and in acetylcholinesterase inhibition [24,25].
Barakat et al. reported the synthesis and biological activities of several spirooxindoles they exhibited interesting pharmacological activities as MDM2–p53 protein-protein interaction inhibitors, phosphodiesterase 1, and as selective cyclooxygenase COX-1 with TNF-α and IL-6 inhibitors. These spirooxindoles were reported to have potential hypoglycemic activity with inhibitory activities against α-amylase and α-glucosidase, and other pharmacological targets [26,27,28,29,30,31,32,33,34].
Another interesting motif is thiochromane and its analogues. Thiochromanone, thiochromane, and thiochromene derivatives are known to exhibit anticancer [35], antiviral [36], non-steroidal estrogen downregulation [36], human steroid sulfatase inhibition [37,38,39,40], α-adrenergic antagonism [41], and has antiparasitic [42], and antifungal [43] properties.
There are many reports on different approaches in the literature on the construction of spirooxindole systems [44,45]. For example, Mannich reactions and related transformations were successfully employed in the construction of naturally occurring spirooxindole alkaloid, (±)-elacomine [46]. An oxidative rearrangement approach of tetrahydro-β-carbolines and related core structures [47], an intra-molecular Heck reaction and similar transformations approach were reported by L. Overman and M. Rosen for the total synthesis of spiro-trypro-statins B [48]. Transition metal-catalyzed synthesis of the spirooxindole scaffold [49] and 1,3-dipolar cycloaddition reactions are regarded as useful approaches for the construction of the spirooxindole scaffold [50]. However, successful approaches for the synthesis of thio-chromenyl/spirooxindole systems are still limited, although replacement of the oxygen atom by sulfur could be a rational strategy for improving pharmacological activity in drug discovery [51,52,53]. The design and synthesis of new compounds as potent and safe anti-cancer agents with low side effects is still a challenge.
Based on literature reports which highlight the biological importance of thiochromene sub-structure and spirooxindole/pyrrolidine scaffolds, our aim was to synthesize a new hybrids comprising three pharmacophores, spirooxindole/pyrrolidine/thiochromene employing three components 1,3-dipolar cycloaddition reaction. This protocol is based on multiple bond formations [54] and hence were able to generate compounds with structural complexity for possible use in agrochemical, drug discovery, and pharmaceutical industries.

2. Materials and Methods

2.1. General

“Thiochroman-3-one, acetophenone derivatives, substituted isatins and L-proline were purchased from Aldrich or TCI, and used as received. All solvents were used as received when experiments were conducted in air. Flash chromatography was performed on 100–200 mesh silica gel. The 1H- and 13C-NMR spectra of the synthesized compound were recorded on a JEOL 400-MHz spectrometer (JEOL, Ltd., Tokyo, Japan) at ambient temperature. The solvents used were DMSO-d6, and CDCl3; the chemical shifts (δ) were given in ppm. Single-crystal X-ray data of compound 7m were collected on a Rigaku Oxford Diffraction Supernova diffractometer at 120 K. Melting points were determined using Mel-Temp apparatus and are uncorrected. Thin Layer Chromatography (TLC) was conducted on silica gel (Kiesel gel G, E.Merck) and spots were detected under UV light at 254 nm. FT-IR spectra were measured on a Perkin Elmer, Spectrum 100 FT-IR spectrometer (FT-IR, Perkin Elmer, USA). Mass spectra were recorded on a Shimadzu GCMS-QP 1000 EX mass spectrometer at 70 eV”.

2.2. Synthesis of 4-Chloro-2H-thiochromene-3-carbaldehyde (2)

Phosphorus oxychloride (32 mL, 350 mmol) was added dropwise at a steady rate to a cold solution (0–5 °C) of N,N-dimethylformamide (11.5 mL, 150 mmol). After 30 min, thiochroman-3-one (8.2 g, 50 mmol) was added. The resulting mixture was allowed to heat to 100 °C for 1.5 h. The reaction mixture was poured slowly into a cold water (300 mL), and the precipitated product was filtered and dried in vacuum at 40 °C for 24 h to obtain a light yellow solid compound 4-chloro-2H-thiochromene-3-carbaldehyde (2) [49].
Yield (8.5 g, yield: 81%); m.p. 139 –141 °C; 1H-NMR (400 MHz, DMSO-d6): δ (ppm) = 10.22 (d, J = 2.2 Hz, 1H, CHO), 7.96–7.88 (m, 1H, Ar-H), 7.51–7.40 (m, 2H, Ar-H), 7.37 (dd, J = 8.5, 6.3 Hz, 1H, Ar-H), 3.72 (d, J = 2.3 Hz, 2H, SCH2); 13C-NMR (101 MHz DMSO-d6): δ (ppm) = 189.0- (CHO), 145.0, 137.0-, 132.0-, 131.0-, 128.6-, 127.7-, 127.0-, 126.5-, 22.8- (SCH2); [Anal. Calcd. for C10H7ClOS: C, 57.01; H, 3.35; Found: C, 57.13; H, 3.24]; LC/MS (ESI, m/z): found 211.22 [M + H+]. All the analytical data were in agreement with the reported literature [37].

2.3. Synthesis of Thiochromene Chalcones (4a-e)

General procedure (GP1): 4-Chloro-2H-thiochromene-3-carbaldehyde (2) (1.05 g, 5.0 mmol) and acetophenone derivatives (3a-e) (5.0 mmol) were dissolved fully (by heating if necessary) in 30 mL ethanol and then NaOH solution in water (30 mL, 20 mmol) was added. The reaction mixture was left for stirring overnight. Light yellow solid precipitates emerged which were filtered and washed with water and ethanol to afford pure chalcone (4a-e).
  • (E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-chlorophenyl)prop-2-en-1-one (4a)
Following GP1, 4-chloro-2H-thiochromene-3-carbaldehyde (2) (1.05 g, 5.0 mmol) reacted with 4-chloroacetophenone (3b) (0.77 g, 5.0 mmol) to produce the chalcone (4b) (yield 1.51 g, 87%); m.p. 118–119; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.24 (d, J = 15.4 Hz, 1H, CH = CH), 7.96–7.89 (m, 2H, Ar-H), 7.86–7.81 (m, 1H, Ar-H), 7.47 (d, J = 8.7 Hz, 2H, Ar-H), 7.36–7.31 (m, 1H, Ar-H), 7.25–7.19 (m, 2H, Ar-H), 7.10 (d, J = 15.4 Hz, 1H, CH = CH), 3.72 (s, 2H, SCH2); 13C{1H}-NMR (126 MHz, CDCl3): δ (ppm) = 189.2 (CO), 141.0-, 139.5-, 138.0-, 136.4-, 135.1-, 132.7, 130.0-, 130.0-, 129.1-, 128.9-, 127.4, 126.3, 126.2-, 124.1, 26.9 (SCH2); IR (KBr, cm–1) νmax = 3087, 2363, 2340, 1654, 1592, 1577, 1568, 1540, 1488, 1456, 1431, 1412, 1401, 1325, 1308, 1294, 1261, 1245, 1212, 1180, 1090, 1029, 1014, 964, 911, 845, 822, 759, 752, 720, 649, 608; [Anal. Calcd. for C18H12Cl2OS: C, 62.26; H, 3.48; Found: C, 62.33; H, 3.39]; LC/MS (ESI, m/z): found 347.21 [M + H+].
  • (E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-fluorophenyl)prop-2-en-1-one (4b)
Following GP1, 4-chloro-2H-thiochromene-3-carbaldehyde (2) (1.05 g, 5.0 mmol) reacted with 4-fluoroacetophenone (3c) (0.69 g, 5.0 mmol) to produce the chalcone (4c) (yield 1.47 g, 89%); m.p. 104–105; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.24 (d, J = 15.8 Hz, 1H, CH = CH), 8.06–7.99 (m, 2H, Ar-H), 7.86–7.81 (m, 1H, Ar-H), 7.36–7.31 (m, 1H, Ar-H), 7.25–7.21 (m, 2H, Ar-H), 7.18 (t, J = 8.6 Hz, 2H, Ar-H), 7.13 (d, J = 15.8 Hz, 1H, CH = CH), 3.73 (s, 2H, SCH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 188.9 (CO), 166.9 &164.0 (d, JC1-F = 238.96 Hz), 140.7, 137.7, 135.1, 134.5, 132.7, 131.3 & 131.2 (d, JC3-F = 9.32 Hz), 123.0, 129.0, 127.4, 126.3, 124.2, 116.0 & 116.0 (d, JC2-F = 21.67 Hz), 26.9 (SCH2); IR (KBr, cm–1) νmax = 3059, 2360, 2336, 1652, 1596, 1572, 1564, 1537, 1502, 1432, 1415, 1404, 1223, 1312, 1296, 1262, 1223, 1213, 1152, 1029, 1009, 969, 947, 909, 861, 852, 827, 805, 762, 603; [Anal. Calcd. for C18H12ClFOS: C, 65.35; H, 3.66; Found: C, 65.47; H, 3.59]; LC/MS (ESI, m/z): found 331.14 [M + H+].
  • (E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-nitrophenyl)prop-2-en-1-one (4c)
Following GP1, 4-chloro-2H-thiochromene-3-carbaldehyde (2) (1.05 g, 5.0 mmol) reacted with 4-nitroacetophenone (3f) (0.83 g, 5.0 mmol) to produce the chalcone (4f) (yield 1.48 g, 83%); m.p. 180–181; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.35 (d, J = 8.7 Hz, 2H, Ar-H), 8.28 (d, J = 16.1 Hz, 1H, CH = CH), 8.15–8.08 (m, 2H, Ar-H), 7.88–7.81 (m, 1H, Ar-H), 7.37–7.33 (m, 1H, Ar-H), 7.28–7.24 (m, 3H, Ar-H), 7.10 (d, J = 15.5 Hz, 1H, CH = CH),), 3.74 (s, 2H, SCH2); 13C-NMR (101 MHz, CDCl3): δ (ppm) = 189.1 (CO), 150.3, 143.0, 142.2, 139.0, 135.3, 132.6, 130.2, 129.6, 129.1, 127.4, 126.4, 126.0, 124.0, 123.8, 26.8 (SCH2); IR (KBr, cm–1) νmax = 3107, 2360, 1664, 1602, 1563, 1539, 1519, 1433, 1407, 1344, 1323, 1308, 1264, 1243, 1209, 1032, 1011, 965, 912, 899, 835, 759, 704; [Anal. Calcd. for C18H12ClNO3S: C, 60.42; H, 3.38; N, 3.91; Found: C, 60.31; H, 3.27; N, 3.84]; LC/MS (ESI, m/z): found 358.17 [M + H+].
  • (E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-bromophenyl)prop-2-en-1-one (4d)
Following GP1, 4-chloro-2H-thiochromene-3-carbaldehyde (2) (1.05 g, 5.0 mmol) reacted with 4-bromoacetophenone (3d) (1.0 g, 5.0 mmol) to produce the chalcone (4d) (yield 1.66 g, 85%); m.p. 141–142; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.24 (d, J = 15.5 Hz, 1H, CH = CH), 7.88–7.80 (m, 3H, Ar-H), 7.64 (d, J = 8.1 Hz, 2H, Ar-H), 7.33 (d, J = 4.4 Hz, 1H, Ar-H), 7.24 (dd, J = 8.8, 4.3 Hz, 2H, Ar-H), 7.09 (d, J = 16.0 Hz, 1H, CH = CH), 3.72 (s, 2H, SCH2); 13C-NMR (101 MHz, CDCl3): δ (ppm) = 189.4 (CO), 141.0, 138.0, 136.9, 135.2, 132.7, 132.1, 130.2, 130.0, 129.0, 128.2, 127.4, 126.3, 126.2, 124.0, 26.9 (SCH2); IR (KBr, cm–1) νmax = 3083, 2372, 1653, 1584, 1576, 1539, 1484, 1430, 1324, 1308, 1294, 1244, 1212, 1181, 1068, 1028, 1008, 964, 945, 911, 844, 819, 758, 752, 718, 608; [Anal. Calcd. for C18H12BrClOS: C, 55.19; H, 3.09; Found: C, 54.97; H, 3.02]; LC/MS (ESI, m/z): found 391.19 [M + H+].
  • (E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-(trifluoromethyl)phenyl)-prop-2-en-1-one (4e)
Following GP1, 4-chloro-2H-thiochromene-3-carbaldehyde (2) (1.05 g, 5.0 mmol) reacted with 4-(trifluoromethyl)acetophenone (3e) (0.94 g, 5.0 mmol) to produce the chalcone (4e) (yield 1.52 g, 80%); m.p. 149–150; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.27 (d, J = 16.0 Hz, 1H, CH = CH), 8.07 (d, J = 8.1 Hz, 2H, Ar-H), 7.86–7.81 (m, 1H, Ar-H), 7.77 (d, J = 8.1 Hz, 2H, Ar-H), 7.37–7.32 (m, 1H, Ar-H), 7.28–7.21 (m, 2H, Ar-H), 7.11 (d, J = 16.0 Hz, 1H, CH = CH), 3.74 (s, 2H, SCH2); 13C-NMR (101 MHz, CDCl3): δ (ppm) = 189.6 (CO), 141.6, 141.0, 138.4, 135.2, 132.6, 130.1, 129.0, 129.0, 127.4, 126.3, 126.1, 125.9, 125.9, 124.0, 26.8 (SCH2); IR (KBr, cm–1) νmax = 3055, 1656, 1590, 1579, 1569, 1543, 1433, 1409, 1319, 1306, 1266, 1247, 1210, 1188, 1175, 1123, 1111, 1065, 965, 943, 912, 829, 757, 718, 681; [Anal. Calcd. for C19H12ClF3OS: C, 59.93; H, 3.18; Found: C, 60.14; H, 3.13]; LC/MS (ESI, m/z): found 381.13 [M + H+].

2.4. Synthesis of Spirooxindole/Pyrrolidine/Thiochromene (7a-m)

Substituted (E)-3-(4-chloro-2H-thiochromen-3-yl)-1-phenylprop-2-en-1-one (4a-e) (0.5 mmol), isatin derivatives (6a-e) (0.5 mmol), and L-proline 5 (57.5 mg, 0.5 mmol) were dissolved in methanol (20 mL) and the reaction mixture was refluxed for 3–6 h. Finally, the products were isolated by flash column chromatography using 100–200 mesh silica gel and MeOH/CH2Cl2 (2:98) as an eluent to afford pure 4-chloro-2H-thiochromen spirooxindoles (7a-m).
  • 1′-(4-Chloro-2H-thiochromen-3-yl)-2′-(4-chlorobenzoyl)-1′,2′,5′,6′,7′,7a′-hexahydro-spiro[indoline-3,3′-pyrrolizin]-2-one (7a)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-chlorophenyl)prop-2-en-1-one (4a) (174 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and isatin (6a) (74 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7a) (149 mg, 86%); m.p.75–76 °C; 1H-NMR (500 MHz, CDCl3): δ (ppm) = 8.22 (s, 1H, NH), 7.73 (d, J = 7.7 Hz, 1H, Ar-H), 7.38 (dd, J = 8.6, 1.8 Hz, 2H, Ar-H), 7.26–7.23 (m, 2H, Ar-H), 7.19–7.14 (m, 3H, Ar-H), 7.12 (t, J = 7.4 Hz, 2H, Ar-H), 6.99 (t, J = 7.4 Hz, 1H, Ar-H), 6.62 (d, J = 8.0 Hz, 1H, Ar-H), 4.72 (d, J = 11.1 Hz, 1H, COCH), 4.64 (t, J = 10.0 Hz, 1H, NCHCH), 4.15 (td, J = 9.0, 8.1, 3.4 Hz, 1H, NCH), 3.61 (d, J = 14.7 Hz, 1H, SCH2(a)), 3.53 (d, J = 14.7 Hz, 1H, SCH2(b)), 2.81–2.72 (m, 1H, NCH2(a)), 2.67–2.60 (m, 1H, NCH2(a)), 2.14–2.08 (m, 1H, CH2), 2.01–1.92 (m, 2H, CH2), 1.92–1.85 (m, 1H, CH2); 13C NMR (126 MHz, CDCl3): δ (ppm) = 195.6 (CO), 180.6- (CO), 140.7-, 139.7, 135.3-, 133.7, 133.0-, 130.2-, 130.0, 129.4, 128.7, 128.7, 128.4, 127.8, 127.8, 127.1, 125.9, 124.7, 122.8, 110.4, 68.3, 59.6, 53.6, 50.7, 48.6, 30.2, 26.9, 26.7 (CH2); IR (KBr, cm–1) νmax = 3201, 3060, 2964, 2873, 1721, 1681, 1618, 1588, 1569, 1486, 1471, 1435, 1400, 1387, 1328, 1291, 1254, 1232, 1207, 1178, 1134, 1112, 1091, 1012, 942, 901, 843, 794, 755, 724, 614, 532; [Anal. Calcd. for C30H24Cl2N2O2S: C, 65.81; H, 4.42; N, 5.12; Found: C, 65.93; H, 4.52; N, 5.01]; LC/MS (ESI, m/z): found 547.16 [M + H+].
  • 6-Chloro-1′-(4-chloro-2H-thiochromen-3-yl)-2′-(4-chlorobenzoyl)-1′,2′,5′,6′,7′,7a′-h-exahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7b)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-chlorophenyl)prop-2-en-1-one (4a) (174 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 6-chloroisatin (6b) (91 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7b) (253 mg, 87%); m.p. 110–111 °C; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 9.53 (s, 1H, NH), 7.96 (d, J = 5.9 Hz, 1H, Ar-H), 7.69 (d, J = 7.3 Hz, 1H, Ar-H), 7.43 (d, J = 8.8 Hz, 2H, Ar-H), 7.19 (d, J = 8.8 Hz, 2H, Ar-H), 7.13 (t, J = 7.0 Hz, 3H, Ar-H), 6.92 (d, J = 8.1 Hz, 1H, Ar-H), 6.69 (s, 1H, Ar-H), 4.70 (d, J = 11.0 Hz, 1H, COCH), 4.61 (t, J = 10.6 Hz, 1H, NCHCH), 4.18–4.12 (m, 1H, NCH), 3.60 (d, J = 15.4 Hz, 1H, SCH2(a)), 3.52 (d, J = 14.7 Hz, 1H, SCH2(b)), 2.76–2.76–2.69 (m, 1H, NCH2(a)), 2.66–2.57 (m, 1H, NCH2(b)), 2.15–2.01 (m, 1H, CH2), 1.95 - 184 (m, 3H, CH2); 13C-NMR (101 MHz, CDCl3): δ (ppm) = 195.4 (CO), 180.2 (CO), 174.3, 162.8, 142.7, 139.8, 135.6, 135.0, 133.6, 132.7, 130.2, 129.3, 128.8, 128.3, 127.6, 126.9, 125.8, 122.8, 122.3, 111.2, 72.9, 67.9, 58.9, 50.7, 48.5, 31.5, 29.7, 26.4 (SCH2); IR (KBr, cm–1) νmax = 3064, 2972, 1730, 1614, 1588, 1486, 1458, 1437, 1401, 1234, 1091, 1074, 1012, 943, 845, 757, 724, 668, 608, 530; [Anal. Calcd. for C30H23Cl3N2O2S: C, 61.92; H, 3.98; N, 4.81; Found: C, 61.84; H, 4.05; N, 4.93]; LC/MS (ESI, m/z): found 581.23 [M + H+].
  • 1′-(4-Chloro-2H-thiochromen-3-yl)-2′-(4-chlorobenzoyl)-5-fluoro-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7c)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-chlorophenyl)prop-2-en-1-one (4a) (174 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-fluoroisatin (6c) (83 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7c) (229 mg, 81%); m.p. 150–1151 ºC; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 9.35 (s, 1H), 7.69 (d, J = 7.5 Hz, 1H), 7.44 (d, J = 8.6 Hz, 2H), 7.22 (d, J = 7.3 Hz, 1H), 7.17 (d, J = 8.3 Hz, 2H), 7.14–7.06 (m, 2H), 6.98 (dd, J = 8.0, 2.7 Hz, 1H), 6.81 (td, J = 8.6, 2.7 Hz, 1H), 6.59 (dd, J = 8.7, 4.3 Hz, 1H), 4.72 (d, J = 11.0 Hz, 1H, COCH), 4.60 (t, J = 10.3 Hz, 1H, NCHCH), 4.19–7.12 (m, 1H, NCH), 3.60 (d, J = 14.6 Hz, 1H, SCH2(a)), 3.52 (d, J = 14.8 Hz, 1H, SCH2(a)), 2.79–2.73 (m, 1H, SCH2(a)), 2.67–2.60 (m, 1H, SCH2(b)), 2.13–2.08 (m, 1H, CH2), 1.99–1.83 (m, 3H, CH2); 13C NMR (126 MHz, CDCl3): δ (ppm) = 195.3 (CO), 159.8 (CO), 157.9, 140.0, 136.6, 135.2, 133.7, 133.0, 130.4, 129.5, 130.0, 128.5, 128.3, 127.9, 127.1, 126.0, 116.7, 116.5, 115.8, 115.6, 111.0, 110.9, 68.3, 53.6, 50.8, 48.5, 29.8, 27.0, 26.7 (SCH2); IR (KBr, cm–1) νmax = 3213, 3061, 2962, 2860, 1724, 1707, 1683, 1652, 1588, 1569, 1486, 1461, 1436, 1400, 1303, 1283, 1249, 1189, 1113, 994, 900, 852, 820, 763, 752, 721, 687, 660, 628, 593, 535; [Anal. Calcd. for C30H23Cl2FN2O2S: C, 63.72; H, 4.10; N, 4.95; Found: C, 63.57; H, 4.21; N, 4.84]; LC/MS (ESI, m/z): found 565.21 [M + H+].
  • 1′-(4-Chloro-2H-thiochromen-3-yl)-5-fluoro-2′-(4-fluorobenzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7d)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-fluorophenyl)prop-2-en-1-one (4b) (164 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-fluoroisatin (6c) (83 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7d) (209 mg, 76%); m.p. 200–201 °C; 1H-NMR (500 MHz, CDCl3): δ (ppm) = 8.45 (s, 1H, NH), 7.73 (dd, J = 7.9, 1.5 Hz, 1H, Ar-H), 7.54 (dd, J = 8.9, 5.3 Hz, 2H, Ar-H), 7.27–7.23 (m, 1H, Ar-H), 7.19–7.15 (m, 1H, Ar-H), 7.13 (dd, J = 7.5, 1.6 Hz, 1H, Ar-H), 7.03 (dd, J = 8.1, 2.5 Hz, 1H, Ar-H), 6.92–6.87 (m, 2H, Ar-H), 6.87–6.83 (m, 1H, Ar-H), 6.59 (dd, J = 8.5, 4.2 Hz, 1H, Ar-H), 4.74 (d, J = 10.8 Hz, 1H, COCH), 4.60 (dd, J = 11.2, 9.7 Hz, 1H, NCHCH), 4.15–4.11 (m, 1H, NCH), 3.58 (d, J = 14.5 Hz, 1H, SCH2(a)), 3.52 (d, J = 14.5 Hz, 1H, SCH2(b)), 2.77–2.71 (m, 1H, NCH2(a)), 2.68–2.61 (m, 1H, NCH2(b)), 2.09–2.15 (m, 1H, CH2), 2.03–1.85 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 194.8 (CO), 181.00 (CO), 166.9 & 164.8 (d, JC1-F = 256.54 Hz, Ph ring), 159.9 & 157.9 (d, JC1-F = 242.8 Hz, indole ring), 136.6, 133.6, 133.3 & 133.3 (d, JC4-F = 3.96 Hz, Ph ring), 132.9, 130.8 & 130.7 (d, JC3-F = 9.45 Hz, Ph ring), 130.4, 128.4, 127.8, 127.1, 126.7 & 126.6 (d, JC6-F = 7.43 Hz, indole ring), 126.0, 116.6 & 116.4 (d, JC2-F = 23.56 Hz, indole ring), 115.8 & 115.6 (d, JC2-F = 21.92 Hz, Ph ring), 115.6, 111 & 110.8 (d, JC5-F = 7.81 Hz, indole ring), 68.3, 59.5, 50.8, 48.4, 30.2, 27.1, 26.7 (SCH2); IR (KBr, cm–1) νmax = 3179, 3074, 2968, 2877, 2862, 1718, 1688, 1634, 1596, 1505, 1487, 1472, 1459, 1298, 1260, 1230, 1207, 1189, 1156, 1137, 1106, 1078, 952, 857, 822, 813, 759, 722, 686; [Anal. Calcd. for C30H23ClF2N2O2S: C, 65.63; H, 4.22; N, 5.10; Found: C, 65.72; H, 4.37; N, 4.97]; LC/MS (ESI, m/z): found 549.17 [M + H+].
  • 6-Chloro-1′-(4-chloro-2H-thiochromen-3-yl)-2′-(4-fluorobenzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7e)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-fluorophenyl)prop-2-en-1-one (4b) (164 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 6-chloroisatin (6b) (91 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7e) (232 mg, 82%); m.p.114–115 °C; 1H-NMR (500 MHz, CDCl3): δ (ppm) = δ 8.35 (s, 1H, NH), 7.72 (dd, J = 7.9, 1.6 Hz, 1H, Ar-H), 7.53 (ddd, J = 8.9, 5.3, 1.4 Hz, 2H, Ar-H), 7.25 (q, J = 1.3 Hz, 1H, Ar-H), 7.20–7.11 (m, 3H, Ar-H), 7.00–6.97 (m, 1H, Ar-H), 6.92 (td, J = 8.6, 1.4 Hz, 2H, Ar-H), 6.67 (d, J = 1.8 Hz, 1H, Ar-H), 4.73 (d, J = 11.0 Hz, 1H, COCH), 4.62 (t, J = 10.5 Hz, 1H, NCHCH), 4.22–4.10 (m, 1H, NCH), 3.60 (d, J = 16.0 Hz, 1H, SCH2(a)), 3.53 (d, J = 14.0 Hz, 1H, SCH2(b)), 2.81–2.72 (m, 1H, NCH2(a)), 2.68–2.60 (m, 1H, NCH2(b)), 2.14–2.10 (m, 1H, CH2), 2.00–1.85 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 194.9 (CO), 180.4 (CO), 167.0 & 165.0 (d, JC1-F = 256.54 Hz), 141.9, 135.8, 133.7, 133.2, 132.9, 130.8 & 130.7 (d, JC3-F = 9.45 Hz), 130.4, 128.9, 128.5, 128.3, 127.8, 127.1, 125.9, 122.8, 115.9 & 115.8 (d, JC2-F = 21.80 Hz), 111.0, 73.0, 68.2, 59.1, 50.9, 48.6, 30.0, 26.8, 26.6 (SCH2); IR (KBr, cm–1) νmax = 3231, 3066, 2964, 2868, 1727, 1681, 1613, 1597, 1506, 1485, 1459, 1411, 1324, 1235, 1207, 1157, 1133, 1074, 944, 921, 848, 813, 757, 625, 600; [Anal. Calcd. for C30H23Cl2FN2O2S: C, 63.72; H, 4.10; N, 4.95; Found: C, 63.64; H, 4.28; N, 5.09]; LC/MS (ESI, m/z): found 565.19 [M + H+].
  • 1′-(4-Chloro-2H-thiochromen-3-yl)-5-fluoro-2′-(4-nitrobenzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7f)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-nitrophenyl)prop-2-en-1-one (4c) (179 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-fluoroisatin (6c) (83 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded yellow colored solid thio-chromen spirooxindole (7f) (213 mg, 74%); m.p. 165–166 °C; 1H-NMR (500 MHz, CDCl3): δ (ppm) = 8.34 (s, 1H, NH), 8.15–8.04 (m, 2H, Ar-H), 7.74 (dd, J = 8.2, 1.9 Hz, 1H, Ar-H), 7.64 (d, J = 8.5 Hz, 2H, Ar-H), 7.30–7.26 (m, 1H, Ar-H), 7.22–7.10 (m, 2H, Ar-H), 6.99 (dd, J = 8.0, 2.7 Hz, 1H, Ar-H), 6.88 (td, J = 8.8, 2.3 Hz, 1H, Ar-H), 6.61 (dd, J = 8.6, 4.1 Hz, 1H, Ar-H), 4.79 (d, J = 11.0 Hz, 1H, COCH), 4.62 (t, J = 10.3 Hz, 1H, NCHCH), 4.30–4.16 (s, 1H, NCH), 3.64 (d, J = 14.7 Hz, 1H, SCH2(a)), 3.59 (d, J = 14.6 Hz, 1H, SCH2(b)), 2.93–2.78 (m, 1H, NCH2(a)), 2.77–2.63 (m, 1H, NCH2(b)), 2.18–2.14 (m, 1H, CH2), 2.04–1.93 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 195.6 (CO), 180.6 (CO), 159.9 & 157.9 (d, JC1-F = 243.56 Hz), 150.3, 141.4, 136.6, 133.6, 132.9, 130.6, 129.0, 128.6, 128.0, 127.9, 127.1, 126.3 & 126.3 (d, JC3-F = 6.93 Hz), 126.0, 123.7, 117.0 & 116.7 (d, JC2-F = 25.07 Hz), 115.7 & 115.5 (d, JC6-F = 23.56 Hz), 111.1 & 111.1 (d, JC5-F = 8.06 Hz), 68.2, 60.6, 50.7, 48.3, 30.2, 27.1, 26.7 (SCH2); IR (KBr, cm–1) νmax = 3392, 3086, 2970, 2893, 2868, 2845, 1740, 1713, 1690, 1326, 1603, 1521, 1485, 1460, 1435, 1347, 1320, 1258, 1180, 1116, 1024, 1011, 988, 945, 900, 868, 856, 760, 720, 709, 683, 630, 594, 557; [Anal. Calcd. for C30H23ClFN3O4S: C, 62.55; H, 4.02; N, 7.29; Found: C, 62.75; H, 4.17; N, 7.13]; LC/MS (ESI, m/z): found 576.13 [M + H+].
  • 6-Chloro-1′-(4-chloro-2H-thiochromen-3-yl)-2′-(4-nitrobenzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7g)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-nitrophenyl)prop-2-en-1-one (4c) (179 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 6-chloroisatin (6d) (91 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded yellow colored solid thio-chromen spirooxindole (7g) (234 mg, 79%); m.p. 143–144 °C; 1H-NMR (500 MHz, CDCl3): δ (ppm) = 8.34 (s, 1H, NH), 8.08 (d, J = 8.8 Hz, 2H, Ar-H), 7.72 (d, J = 7.9 Hz, 1H, Ar-H), 7.60 (d, J = 7.6 Hz, 2H, Ar-H), 7.25 (s, 1H, Ar-H), 7.19–7.10 (m, 3H, Ar-H), 7.01 (dd, J = 8.1, 1.9 Hz, 1H, Ar-H), 6.66 (d, J = 1.8 Hz, 1H, Ar-H), 4.77 (d, J = 11.1 Hz, 1H, COCH), 4.58 (t, J = 10.5 Hz, 1H, NCHCH), 4.15–4.07 (m, 1H, NCH), 3.59 (d, J = 14.9 Hz, 1H, SCH2(a)), 3.53 (d, J = 14.7 Hz, 1H, SCH2(b)), 2.73–2.65 (m, 1H, NCH2(a)), 2.65–2.57 (m, 1H, NCH2(a)), 2.14–2.07 (m, 1H, CH2), 1.98–1.85 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 195.7 (CO), 180.4 (CO), 150.4, 141.9, 141.4, 136.1, 133.7, 132.8, 130.6, 129.0, 128.8, 128.6, 127.9, 127.1, 126.0, 123.8, 123.0, 111.2, 72.9, 68.1, 60.4, 50.9, 48.5, 30.2, 27.0, 26.7 (SCH2); IR (KBr, cm–1) νmax = 3112, 3083, 2967, 2902, 2865, 1745, 1718, 1695, 1612, 1568, 1518, 1484, 1459, 1405, 1343, 1319, 1277, 1244, 1204, 1132, 1077, 1040, 864, 816, 765, 706, 626, 599; [Anal. Calcd. for C30H23Cl2N3O4S: C, 60.81; H, 3.91; N, 7.09; Found: C, 61.01; H, 4.12; N, 7.19]; LC/MS (ESI, m/z): found 592.15 [M + H+].
  • 2′-(4-Bromobenzoyl)-1′-(4-chloro-2H-thiochromen-3-yl)-5-fluoro-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7h)
(E)-1-(4-Bromophenyl)-3-(4-chloro-2H-thiochromen-3-yl)prop-2-en-1-one (4d) (196 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-fluoroisatin (6c) (83 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7h) (241 mg, 79%); m.p. 132–133 °C; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.45 (s, 1H, NH), 7.72 (dd, J = 7.3, 2.0 Hz, 1H, Ar-H), 7.39 (s, 4H, Ar-H), 7.29–7.25 (m, 1H, Ar-H), 7.15 (dtd, J = 16.5, 7.5, 1.5 Hz, 2H, Ar-H), 6.98 (dd, J = 8.1, 2.7 Hz, 1H, Ar-H), 6.86 (td, J = 8.7, 2.7 Hz, 1H, Ar-H), 6.67 (dd, J = 8.8, 4.4 Hz, 1H, Ar-H), 4.72 (d, J = 10.8 Hz, 1H, COCH), 4.69 (t, J = 11.2 Hz, 1H, NCHCH), 4.43–4.22 (m, 1H, NCH), 3.64 (d, J = 14.8 Hz, 1H, SCH2(a)), 3.58(d, J = 14.8 Hz, 1H, SCH2(b)), 3.02–2.88 (m, 1H, NCH2(a)), 2.88–2.73(m, 1H, NCH2(b)), 2.24–2.16 (m, 1H, CH2), 2.17–1.95 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 195.5 (CO), 180.8 (CO), 159.8 &157.9 (d, JC1-F = 242.8 Hz), 136.7, 135.6, 133.6, 132.9, 131.9, 130.4, 129.5, 128.7, 128.4, 128.3, 127.8, 127.1, 126.5 & 126.5 (d, JC3-F = 7.31 Hz), 126.0, 116.6 & 116.4 (d, JC2-F = 23.56 Hz), 115.8 & 115.6 (d, JC6-F = 24.95 Hz), 111.0 & 110.89 (d, JC5-F = 7.68 Hz), 73.7, 68.3, 59.6, 50.8, 48.4, 30.2, 27.1, 26.6 (SCH2); IR (KBr, cm–1) νmax = 3355,3075, 2973, 2899, 2871, 2842, 1711, 1683, 1629, 1584, 1568, 1486, 1460, 1398, 1318, 1277, 1259, 1182, 1143, 1114, 1070, 1028, 1007, 988, 948, 899, 852, 814, 760, 721, 685, 631, 594; [Anal. Calcd. for C30H23BrClFN2O2S: C, 59.08; H, 3.80; N, 4.59; Found: C, 58.97; H, 3.92; N, 4.43]; LC/MS (ESI, m/z): found 609.13 [M + H+].
  • 2′-(4-Bromobenzoyl)-6-chloro-1′-(4-chloro-2H-thiochromen-3-yl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7i)
(E)-1-(4-Bromophenyl)-3-(4-chloro-2H-thiochromen-3-yl)prop-2-en-1-one (4d) (196 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 6-chloroisatin (6b) (91 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded white solid thio-chromen spirooxindole (7i) (266 mg, 85%); m.p. 105–106 °C; 1H-NMR (500 MHz, CDCl3): δ (ppm) = 8.36 (s, 1H, NH), 7.73 (dd, J = 7.9, 1.6 Hz, 1H, Ar-H), 7.43–7.34 (m, 4H, Ar-H), 7.27–7.25 (m, 1H, Ar-H), 7.19 (d, J = 8.1 Hz, 1H, Ar-H), 7.17 (dd, J = 7.7, 1.6 Hz, 1H, Ar-H), 7.13 (td, J = 7.4, 1.6 Hz, 1H, Ar-H), 7.00 (dd, J = 8.1, 1.9 Hz, 1H, Ar-H), 6.69 (d, J = 1.9 Hz, 1H, Ar-H), 4.73 (d, J = 11.1 Hz, 1H, COCH), 4.61 (t, J = 9.5 Hz, 1H, NCHCH), 4.17–4.09 (m, 1H, NCH), 3.59 (d, J = 14.7 Hz, 1H, SCH2(a)), 3.52 (d, J = 14.6 Hz, 1H, SCH2(b)), 2.77–2.69 (m, 1H, NCH2(a)), 2.65–2.60 (m, 1H, NCH2(b)), 2.16–2.08 (m, 1H, CH2), 1.98–1.86 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 195.5 (CO), 180.6 (CO), 141.8, 135.7, 135.5, 133.6, 132.9, 131.9, 130.4, 129.5, 128.8, 128.4, 128.3, 127.8, 127.0, 126.0, 123.1, 122.8, 111.0, 73.0, 68.2, 59.3, 50.9, 48.5, 30.1, 27.0, 26.6 (SCH2); IR (KBr, cm–1) νmax = 3225, 2958, 2869, 1726, 1680, 1613, 1584, 1484, 1459, 1436, 1398, 1323, 1233, 1206, 1133, 1072, 1008, 944, 842, 809, 756, 726, 625, 599; [Anal. Calcd. for C30H23BrCl2N2O2S: C, 57.52; H, 3.70; N, 4.47; Found: C, 57.63; H, 3.62; N, 4.39]; LC/MS (ESI, m/z): found 625 [M(35Cl/79Br) + H]+; 627.22 [M + H+].
  • 2′-(4-Bromobenzoyl)-1′-(4-chloro-2H-thiochromen-3-yl)-5-nitro-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7j)
(E)-1-(4-Bromophenyl)-3-(4-chloro-2H-thiochromen-3-yl)prop-2-en-1-one (4d) (196 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-nitroisatin (6e) (96 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded light yellow solid thio-chromen spirooxindole (7j) (255 mg, 80%); m.p. 120–121 °C; 1H-NMR (500 MHz, DMSO-d6): δ (ppm) = 11.10 (s, 1H, NH), 8.11 (dd, J = 8.7, 2.3 Hz, 1H, Ar-H), 7.90 (d, J = 2.4 Hz, 1H, Ar-H), 7.68–7.64 (m, 1H, Ar-H), 7.53 (d, J = 8.6 Hz, 2H, Ar-H), 7.38 (d, J = 8.6 Hz, 2H, Ar-H), 7.33 (dd, J = 7.1, 2.0 Hz, 1H, Ar-H), 7.27–7.19 (m, 2H, Ar-H), 6.79 (d, J = 8.7 Hz, 1H, Ar-H), 4.83 (d, J = 10.8 Hz, 1H, COCH), 4.49 (t, J = 10.3 Hz, 1H, NCHCH), 4.05–4.00 (m, 1H, NCH), 3.78 (d, J = 15.1 Hz, 1H, SCH2(a)), 3.71 (d, J = 15.1 Hz, 1H, SCH2(b)), 2.68–2.63 (m, 1H, NCH2(a)), 2.48–2.43 (m, 1H, NCH2(b)), 2.06–1.98 (m, 1H, CH2), 1.94–1.89 (m, 1H, CH2), 1.84–1.74 (m, 2H, CH2); 13C-NMR (126 MHz, DMSO-d6): δ = 196.2 (CO), 179.1 (CO), 148.5, 141.7, 135.4, 133.6, 132.2, 131.6, 130.0, 129.6, 128.6, 128.3, 127.73, 127.1, 127.0, 126.9, 126.0, 125.3, 122.3, 110.1, 71.8, 67.2, 59.3, 50.3, 47.7, 29.1, 26.3- (SCH2), 25.8; IR (KBr, cm–1) νmax = 3075, 2978, 2878, 2837, 1718, 1678, 1626, 1596, 1584, 1525, 1480, 1461, 1398, 1338, 1311, 1242, 1127, 1100, 1071, 997, 742, 856, 833, 755, 558; [Anal. Calcd. for C30H23BrClN3O4S: C, 56.57; H, 3.64; N, 6.60; Found: C, 56.71; H, 3.55; N, 6.52]; LC/MS (ESI, m/z): found 636.10 [M + H+].
  • 5-Chloro-1′-(4-chloro-2H-thiochromen-3-yl)-2′-(4-(trifluoromethyl)benzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7k)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-(trifluoromethyl)phenyl)prop-2-en-1-one (4e) (191 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-chloroisatin (6d) (91 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded light yellow solid thiochromen spirooxindole (7k) (237 mg, 77%); m.p. 141–142 °C; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.24 (s, 1H, NH),7.74 (d, J = 8.0 Hz, 1H, Ar-H), 7.61 (d, J = 8.1 Hz, 2H, Ar-H), 7.53 (d, J = 8.2 Hz, 2H, Ar-H), 7.28 (d, J = 7.5 Hz, 1H, Ar-H), 7.20–7.08 (m, 4H, Ar-H), 6.63 (d, J = 8.5 Hz, 1H, Ar-H), 4.77 (d, J = 10.8 Hz, 1H, COCH), 4.68 (t, J = 10.4 Hz, 1H, NCHCH), 4.44–4.22 (m, 1H, NCH), 3.66 (d, J = 14.8 Hz, 1H, SCH2(a)), 3.61 (d, J = 14.8 Hz, 1H, SCH2(b)), 3.06–2.88 (m, 1H, NCH2(a)), 2.88–2.72 (m, 1H, NCH2(b)), 2.25–2.16 (m, 1H, CH2), 2.12–1.95 (m, 3H, CH2); 13C-NMR (126 MHz, CDCl3): δ (ppm) = 196.0 (CO), 180.4- (CO), 139.7-, 139.2-, 133.6-, 132.9-, 130.5, 130.0-, 128.5, 128.4, 128.3-, 128.2, 128.1, 127.9, 127.1, 126.6, 126.0, 125.6, 125.6, 124.6, 122.4, 111.3, 73.2, 68.2, 60.1, 50.9, 48.5, 30.0, 27.0, 26.7 (SCH2); IR (KBr, cm–1) νmax = 3078, 2973, 2877, 2833, 1740, 1685, 1617, 1585, 1510, 1474, 1235, 1172, 1132, 1066, 1014, 1003, 950, 891, 863, 819, 761, 682, 626, 553; [Anal. Calcd. for C31H23Cl2F3N2O2S: C, 60.49; H, 3.77; N, 4.55; Found: C, 60.67; H, 3.85; N, 4.66]; LC/MS (ESI, m/z): found 615.18 [M + H+].
  • 1′-(4-Chloro-2H-thiochromen-3-yl)-5-nitro-2′-(4-(trifluoromethyl)benzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7l)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-(trifluoromethyl)phenyl)prop-2-en-1-one (4e) (191 mg, 0.5 mmol), L-proline (5) (57.5 mg, 0.5 mmol) and 5-nitroisatin (6e) (96 mg, 0.5 mmol) were reacted according to GP2 for 3–6 h and yielded light yellow solid thiochromen spirooxindole (7l) (235 mg, 75%); m.p. 139–140 °C; 1H-NMR (500 MHz, DMSO-d6): δ (ppm) = 11.06 (s, 1H, NH), 8.10 (dd, J = 8.7, 2.3 Hz, 1H, Ar-H), 7.91 (d, J = 2.3 Hz, 1H, Ar-H), 7.71–7.65 (m, 3H, Ar-H), 7.61 (d, J = 8.3 Hz, 2H, Ar-H), 7.34 (dd, J = 7.1, 2.0 Hz, 1H, Ar-H), 7.24 (ddd, J = 9.0, 7.3, 1.7 Hz, 2H, Ar-H), 6.74 (d, J = 8.7 Hz, 1H, Ar-H), 4.91 (d, J = 10.8 Hz, 1H, COCH), 4.54–4.45 (m, 1H, NCHCH), 4.08–4.01 (m, 1H, NCH), 3.82 (d, J = 15.1 Hz, 1H, SCH2(a)), 3.71 (d, J = 15.1 Hz, 1H, SCH2(b)), 2.67–2.61 (m, 1H, NCH2(a)), 2.49–2.44 (m, 1H, NCH2(b)), 2.08–1.99 (m, 1H, CH2), 1.95–1.88 (m, 1H, CH2), 1.86–1.74 (m, 2H, CH2); 13C NMR (126 MHz, DMSO-D6) δ 196.6 (CO), 179.0 (CO), 148.5, 141.8, 139.6, 133.6, 132.2, 130.0, 128.6, 128.5, 128.4, 127.1, 127.0, 126.0, 125.4, 125.2, 124.6, 122.4, 122.2, 110.2, 71.7, 67.3, 59.8, 50.2, 47.6, 29.2, 26.4 (SCH2), 25.8; IR (KBr, cm–1) νmax = 3075, 2972, 2875, 2837, 1737, 1719, 1688, 1625, 1598, 1526, 1480, 1461, 1409, 1339, 1325, 1171, 1130, 1102, 1066, 1014, 943, 903, 861, 835, 755, 721, 628, 556; [Anal. Calcd. for C31H23ClF3N3O4S: C, 59.47; H, 3.70; N, 6.71; Found: C, 59.38; H, 3.82; N, 8.63]; LC/MS (ESI, m/z): found 626.12 [M + H+].
  • 1′-(4-Chloro-2H-thiochromen-3-yl)-2′-(4-fluorobenzoyl)-1′,2′,5′,6′,7′,7a′-hexahydrospiro[indoline-3,3′-pyrrolizin]-2-one (7m)
(E)-3-(4-Chloro-2H-thiochromen-3-yl)-1-(4-fluorophenyl)prop-2-en-1-one (4b) (164 mg, 0.5 mmol), L-proline (5) (86 mg, 0.75 mmol) and isatin (6a) (74 mg, 0.5 mmol) were reacted according to GP2 for 2 h and yielded white solid thiochromen spirooxindole (7m) (226 mg, 85%); m.p.: 110–111 °C; 1H-NMR (400 MHz, CDCl3): δ (ppm) = 8.32 (s, 1H, NH), 7.74 (dd, J = 7.8, 1.7 Hz, 1H, Ar-H), 7.50 (dd, J = 8.7, 5.3 Hz, 2H, Ar-H), 7.30–7.21 (m, 2H, Ar-H), 7.15 (ddd, J = 19.9, 9.2, 7.3 Hz, 3H, Ar-H), 6.99 (t, J = 7.7 Hz, 1H, Ar-H), 6.89 (t, J = 8.7 Hz, 2H, Ar-H), 6.66 (d, J = 7.9 Hz, 1H, Ar-H), 4.73 (d, J = 10.8 Hz, 1H, COCH), 4.69 (t, J = 10.8 Hz, 1H, NCHCH), 4.30–4.20 (m, 1H, NCH), 3.64 (d, J = 14.8 Hz, 1H, SCH2(a)), 3.56 (d, J = 14.8 Hz, 1H, SCH2(b)), 2.93–2.80 (m, 1H, NCH2(a)), 2.77–2.69 (m, 1H, NCH2(b)), 2.17–2.12 (m, 1H, CH2), 2.07–1.91 (m, 3H, CH2); 13C-NMR (101 MHz, CDCl3): δ (ppm) = 195.11 (CO), 181.00 (CO), 166.73 & 164.70 (d, JC1-F = 255.78 Hz), 140.65, 133.62, 133.44, 133.04, 130.69 & 130.62 (d, JC3-F = 9.20 Hz), 130.17, 129.80, 128.83, 128.34, 127.84, 127.78, 127.05, 125.91, 124.86, 122.78, 115.6 5 & 115.48 (d, JC2-F = 21.80 Hz), 110.30, 68.42, 59.61, 50.74, 48.52, 30.29, 27.02, 26.68 (SCH2); IR (KBr, cm–1) νmax = 3187, 3145, 3074, 2963, 2872, 1718, 1689, 1620, 1596, 1504, 1471, 1461, 1435, 1408, 1388, 1322, 1297, 1263, 1234, 1207, 1184, 1155, 1105, 951, 853,, 797, 761, 751, 722, 604; [Anal. Calcd. for C30H24ClFN2O2S: C, 67.85; H, 4.56; N, 5.28; Found: C, 67.73; H, 4.45; N, 5.16]; LC/MS (ESI, m/z): found 531.24 [M + H]+.

2.5. Biological Activity Assays Protocols

Cytotoxicity against BJ human fibroblast normal cell line against PC3, HeLa, MCF-7 and MDA-MB231 cancer cell lines were evaluated by following the procedure as described in the literature [55,56,57,58,59] (Supplementary Materials).

3. Results and Discussion

3.1. Synthesis of (4a-e) and (7a-m)

Three steps synthesis of the target compounds are presented in Scheme 1 and Scheme 2. The first step was to synthesize 4-chloro-2H-thiochromene-3-carbaldehyde (2) which is required to prepare chalcone based thiochromene scaffolds (4a-e) (Scheme 1). The second step is a three-component reaction in which the 1,3-dipolar cycloaddition key-reaction between thiochromene based-chalcone and the azomethine ylides, generated the substituted isatins (6a-e) (Isatin (6a), 5-chloroisatin (6b), 6-chloroisatin (6c), 5-fluoroisatin (6d), and 5-nitroisatin (6e) and amino acid L-proline (5) (Scheme 2). Thus, the diversity points in our library are the substituents at the isatin ring, and the aromatic substituents in the thiochromene based-chalcone. All three component reactions were carried out by heating an equimolar mixture of the thiochromene based-chalcone, isatin derivative, and L-proline in MeOH under reflux conditions for 3–6 h. After completion of the reaction as checked by TLC, the solvent was evaporated and the cyclized spiro-compounds were purified by column chromatography to afford pure cycloadducts in a very good yield. The following aromatic substituents in the thiochromene based-chalcone in the para-position (Cl, F, NO2, Br, and CF3) were employed to explore the substrate scope, and to establish generality of this approach. The structures of the spirooxindoles (7a-m) were assigned based on spectrophotometric tools including 1H- & 13C-NMR, MS and IR spectral analyses which have been found with a high constituency with the proposed chemical structures. Additionally, compound (7m) was obtained in crystalline form suited for single crystal X-ray diffraction analysis. The final cycloadducts were obtained in excellent regio-selectivity and diastereo-selectivity. The reaction mechanism assumed to proceed via two steps shown in Scheme 3. The first step is to generate the azomethine yields by the reaction of isatins with L-proline to afford the cyclic lactone, followed by decarboxylation. The cycloaddition step-2 occurs in a such way as to make the two carbonyls of the oxindole ring and the chalcone moiety trans to each other to minimize the steric repulsion in the final product. Besides, the stereochemistry of the stereo-genic centers is unambiguously confirmed by single crystal X-ray analysis for compound (7m) as a representative example. 1H-NMR spectrum showed the assigned protons and matched with the proposed structure. A singlet at δ 8.32 was assigned to the NH proton. The signals occurred at δ 7.74-6.66 were assigned for the aromatic protons while the protons of the fused pyrrolidine ring were assigned at δ 4.73-1.91. The two protons of the methine group adjacent to the sulfur atom of the thiochromene ring were observed at δ 3.64 and 3.56. 13C-NMR spectrum showed the characteristic carbon signals of the proposed compound. IR spectrum showed the desired final compound’s functionalities and the functional groups disappeared as active carbon in isatin derivatives, as well as the olefin functional group in the chalcones.

3.2. X-ray Structure Description

The X-ray structure of (7m), crystallized in the monoclinic crystal system and of centrosymmetric C2/c space group, with eight molecular units per unit cell was elucidated. The unit cell parameters are a = 36.6524(7) Å, b = 8.27830(10) Å, c = 17.1963(3) Å, 102.216(2)° and V = 5099.55(15) Å3. The X-ray structure was in agreement with the spectral characterization and the formation of the spiro system of the compound (Figure 2). The two spiro-moieties (oxindole and pyrolizine) are linked together via the C15 asymmetric center. The thiochromene moiety was also found to be connected to the pyrolizine via the C10 chiral carbon. The molecular units of this compound form a dimer via noncovalent interactions (Figure 3). In this figure two molecules of (7m) are connected via N-H…O hydrogen bonding interactions. Crystal data and structure refinement for compound (7m) are listed in Table 1. Selected bond lengths [Å] and angles [°] for (7m) are summarized in Table 2.

3.3. Biological Activity

All chalcones-based-thiochromenes (4a-e), and the spirooxindole/pyrrolidine/thiochromenes (7a-m) were initially examined for their toxicity against the human fibroblast BJ normal cell line. The results depicted in Table 1 indicated that all the synthesized compounds were non-toxic, except compounds (7d) and (7k) which appeared to be slightly toxic at 30 µM concentration. The toxicities of these two compounds may be due to the presence of F, CF3 and Cl substituents at the phenyl ring-based chalcone, and the chlorine atom attached to C-5 incorporated isatin moiety.
The antiproliferative activity against four human cancer lines, including prostate PC-3, cervical HeLa, and breast (MCF-7 and MDA-MB231) were evaluated by MTT assay [55,56,57,58,59] and the results were compared with the standard anti-cancer drug doxorubicin as a reference.
MCF-7 is a human breast cancer cell line with glucocorticoid, progesterone and estrogen receptors it is widely used worldwide for in vitro anti-cancer assay. The cell line is known to retain mammary epithelial characteristics, particularly estrogen (the first hormone to respond to breast cancer) processing via estrogen receptors [60,61]. In contrast the MDA-MB-231 cell line is particularly used to model late stage cancer, and is considered to be a good triple negative model because of the lack of growth factor receptor HER2 and absence of ER, PR, and E-cadherin [62].
All chalcones-based thiochromenes (4a-e) were found to be inactive against PC-3, HeLa, MCF-7, and MDA-MB231 cell lines, except 4-fluoro and 4-nitro substituted phenyl moiety containing compounds (4b) (IC50 = 27.7 ± 0.9 µM) and (4c) (IC50 = 27.7 ± 0.9 µM), which appeared to be weakly active against PC-3 cervical cancer cell line.
The results of antiproliferative activity against the prostate cancer PC3 cell line by the spiro-oxindole/pyrrolidine/thiochromene series (7a-m) showed that the most active hybrid in these series was compound (7f) (IC50 = 8.7 ± 0.7 µM), having para-NO2 aromatic substituent, and the fluorine at C-5 of the isatin ring, whereas complete loss of activity was observed for compound (7g) having a chlorine atom at C-5 of the isatin ring. The replacement of para-NO2 with para-bromo at the aromatic ring also contributed towards a decrease in activity, as observed for compounds (7h) (IC50 = 16 ± 0.7 µM). Further decrease in activity was observed for compounds with 4-chloro (7i, IC50 = 27.7 ± 0.9 µM) and 5-nitro (7j, IC50 = 22.5 ± 0.4 µM) groups, attached to the isatin ring. Present of a chlorine atom at C-6 of the isatin ring, in combination with the para-fluoro-substituted benzene ring, decreased the activity of compounds (7e, IC50 = 27.5 ± 0.5 µM), and (7i, IC50 = 27.7 ± 0.9 µM) against PC-3 cells. On the other hand, compound (7k) with a chlorine atom at C-5 at the isatin ring and p-trifluoromethyl benzene appeared to be the second most active member of the series (IC50 = 15.6 ± 0.3 µM), whereas replacement of the C-5 chlorine isatin ring with C-5 nitro isatin moiety resulted in a complete loss of activity, as observed in compound 7l. Compounds (7a-d, 7g, 7l, and 7m) were not active.
Next, the anticancer assay against cervical cancer HeLa cell line exhibited moderate to weak anticancer activity in comparison to the standard drug doxorubicin (IC50 = 0.9 ± 0.14 µM). The most potent spirooxindole/pyrrolidine/thiochromene hybrid (7k) having C-5 chlorine incorporated isatin moiety with p-trifluoromethyl phenyl ring gave the best results with IC50 = 8.4 ± 0.5 µM, followed by C-4 chlorine incorporated isatin and p-nitro phenyl moieties containing (7g, IC50 = 10.4 ± 0.7 µM). The replacement of C-4 chlorine containing isatin moiety with C-5 fluoro isatin led to a decrease in anti-cancer potential of (7f, IC50 = 22.6 ± 0.1 µM) against HeLa cell line, found to be further decreased in compound (7h, IC50 = 25.3 ± 0.25 µM), containing p-bromo-phenyl ring instead of p-nitro phenyl moiety, whereas a sharp increase in activity was observed for adduct (7j, IC50 = 12.0 ± 0.1 µM) having C-5 nitro isatin instead of C-5 fluoro isatin( 7h, IC50 = 25.3 ± 0.25 µM). Complete loss of activity was observed for compound (7e) having a p-fluorophenyl ring instead of p-nitrophenyl (7g, IC50 = 10.4 ± 0.7 µM), (7i) having a C-5 chloro isatin ring instead of C-6 nitro isatin (7j, IC50 = 12.0 ± 0.1 µM), and (7l) having a C-6 nitro isatin ring instead of C-6 chloro isatin moiety (7k, IC50 = 8.4 ± 0.5 µM). Comparison of compound (7a) with (7m), which have IC50 = 24.8 ± 0.3 µM and 18.5 ± 0.9 µM, respectively, indicated slight improvement in the reactivity due to the replacement of the chlorine atom with fluorine.
Many of the tested chalcones-based-thiochromenes (4a-e), and the spirooxindole/pyrrolidine/thiochromenes (7a-m) appeared to be inactive against MCF-7 and MDA-MB231 breast cancer cell lines, except (7d-f, 7h, and 7k). C-5 fluoro incorporated isatin moiety with p-fluoro phenyl ring containing (7d) appeared as the most potent against MCF-7 (IC50 = 7.36 ± 0.37 µM) and MDA-MB231 (IC50 = 9.44 ± 0.32 µM) breast cancer cell lines. A slight decrease in activity against both cell lines was observed in compound (7h, MCF-7, IC50 = 8.34 ± 0.64 µM, and MDA-MB231, IC50 = 11.25 ± 0.28 µM) having a p-fluoro phenyl ring instead of a p-bromo phenyl ring. The observed anti-cancer potential in-case of compound (7h) was further decreased in compound (7e, MCF-7, IC50 = 16.4 ± 0.61 µM and MDA-MB231, IC50 = 21.29 ± 1.35 µM) having C-4 chloro incorporated isatin moiety with p-fluoro phenyl ring and C-5 chloro isatin with p-trifluoromethyl phenyl moieties containing (7k, MCF-7, IC50 = 26.04 ± 1.07 µM, and MDA-MB231, IC50 = 25.28 ± 0.77 µM). On the other hand, substitution of p-nitro group on the phenyl ring together with C-5 fluoro incorporated isatin moiety contributed towards a drastic increase in anti-cancer potential against MDA-MB231 cell line (IC50 = 9.29 ± 0.34 µM) and slight increase in anticancer activity against MCF-7 cell line (IC50 = 23.27 ± 0.80 µM), as observed in (7f), whereas, in comparison to (7f), the replacement of C-5 fluoro incorporated isatin moiety with 4-choloro isatin ring contributed towards a considerable increase in activity of compound (7g) against MCF-7 (IC50 = 14.3 ± 0.16 µM), and a complete loss of activity against MDA-MB231 breast cancer cell line. Compound (7m) of p-F-atom on the phenyl ring without any substitution on the isatin core structure showed a weak activity for both breast cancer cell lines (MCF-7; IC50 = 24.16 ± 0.25 µM and MDA-MB231; IC50 = 21.09 ± 0.1 µM). All results are summarized in Table 3.

4. Conclusions

During this study we have successfully achieved the synthesis of a new library of hybrid based spirooxindole/pyrrolidine/thiochromenes (7a-m) by three-component 1,3-dipolar cycloaddition reactions in complete regio- and stereo-selective fashion. The anti-cancer assay showed promising results as good candidates for further studies. Compounds (7f, IC50 = 8.7 ± 0.7 µM) exhibited more potent activity against PC3, whereas hybrid (7k) was most active against cervical cancer HeLa (IC50 8.4 ± 0.5 µM) and for breast cancer MCF-7 cell lines (7d, IC50 = 7.36 ± 0.37 µM), whereas (7d, IC50 = 9.44 ± 0.32 µM) also appeared more active against MDA-MB231 breast cancer cell line. The mechanism of action and in vivo study will be considered in the near future to further validate results of in vitro assays.

Supplementary Materials

The following are available online at https://www.mdpi.com/article/10.3390/sym13081426/s1, Figures S1–S18: 1H-NMR and 13C-NMR for compounds 4a-e and 7a-m along with the X-ray structure determinations and biological activity assays protocols are provided in SI.

Author Contributions

Conceptualization, A.B. and M.I.C.; methodology, M.S.I., M.A., A.M.A.-M., S.A. and A.S.A.; validation, M.S.I., M.A., A.M.A.-M., S.A. and A.S.A.; formal analysis, M.S.I., M.A., A.M.A.-M., S.A. and A.S.A.; investigation, M.S.I., M.A., A.M.A.-M., S.A. and A.S.A.; resources, A.B.; data curation, M.S.I., M.A., A.M.A.-M., S.A. and A.S.A.; writing—original draft preparation, A.B. and S.Y.; writing—review and editing, M.I.C.; visualization, A.B. and M.I.C.; project administration, M.A.; funding acquisition, A.B.; All authors have read and agreed to the published version of the manuscript.

Funding

King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number (14-BIO128-02).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

The data presented in this study are available in Supplementary Material.

Acknowledgments

This Project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number (14-BIO128-02). The authors would like to thank Matti Haukka (Department of Chemistry, University of Jyväskylä, Finland) for solved the structure of compound 7m by single crystal X-ray diffraction analysis.

Conflicts of Interest

The authors declare no conflict of interest.

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Symmetry 13 01426 g001 550
Figure 1. Bioactive compounds incorporating spirooxindole, and thiochromane skeletons.
Figure 1. Bioactive compounds incorporating spirooxindole, and thiochromane skeletons.
Symmetry 13 01426 g001
Symmetry 13 01426 sch001 550
Scheme 1. Synthesis of chalcone grafted 2H-thiochromenes (4a-e).
Scheme 1. Synthesis of chalcone grafted 2H-thiochromenes (4a-e).
Symmetry 13 01426 sch001
Symmetry 13 01426 sch002 550
Scheme 2. Synthesis of spirooxindoles (7a-m) based the thiochromene scaffold.
Scheme 2. Synthesis of spirooxindoles (7a-m) based the thiochromene scaffold.
Symmetry 13 01426 sch002
Symmetry 13 01426 sch003 550
Scheme 3. Proposed mechanism for the regio- and diastereo-selective synthesis of the spirooxindole (7a-m) based thiochromene scaffold.
Scheme 3. Proposed mechanism for the regio- and diastereo-selective synthesis of the spirooxindole (7a-m) based thiochromene scaffold.
Symmetry 13 01426 sch003
Symmetry 13 01426 g002 550
Figure 2. Thermal ellipsoids are showing atom numbering for the X-ray structure of compound (7m).
Figure 2. Thermal ellipsoids are showing atom numbering for the X-ray structure of compound (7m).
Symmetry 13 01426 g002
Symmetry 13 01426 g003 550
Figure 3. Hydrogen bonding interactions in compound (7m).
Figure 3. Hydrogen bonding interactions in compound (7m).
Symmetry 13 01426 g003
Table
Table 1. Crystal data and structure refinement for compound (7m). Hydrogen bond details: N(2)-H(2): 0.80(2) Å; H(2)...O(1)#1: 2.08(2) Å; N(2...O(1)#1: 2.877(1) Å and N(2)-H(2)...O(1)#1: 174(2)° and the symmetry code is #1−x + 1,−y + 1,−z + 1.
Table 1. Crystal data and structure refinement for compound (7m). Hydrogen bond details: N(2)-H(2): 0.80(2) Å; H(2)...O(1)#1: 2.08(2) Å; N(2...O(1)#1: 2.877(1) Å and N(2)-H(2)...O(1)#1: 174(2)° and the symmetry code is #1−x + 1,−y + 1,−z + 1.
Empirical FormulaC30H24ClFN2O2S
Formula weight531.02
Temperature120(2) K
Wavelength0.71073 Å
Crystal systemMonoclinic
Space groupC2/c
Unit cell dimensionsa = 36.6524(7) Åα = 90°.
b = 8.27830(10) Åβ = 102.216(2)°
c = 17.1963(3) Åγ = 90°
Volume5099.55(15) Å3
Z8
Density (calculated)1.383 Mg/m3
Absorption coefficient0.271 mm−1
F(000)2208
Crystal size0.228 × 0.166 × 0.139 mm3
Theta range for data collection2.274 to 32.514°.
Index ranges−54 < = h < = 44, −12 < = k < = 12, −24 < = l < = 25
Reflections collected29,780
Independent reflections8550 [R(int) = 0.0261]
Completeness to theta = 25.242°100.00%
Absorption correctionSemi-empirical from equivalents
Max. and min. transmission1.00000 and 0.96869
Refinement methodFull-matrix least-squares on F2
Data/restraints/parameters8550/0/338
Goodness-of-fit on F21.017
Final R indices [I > 2sigma(I)]R1 = 0.0445, wR2 = 0.1170
R indices (all data)R1 = 0.0543, wR2 = 0.1251
Extinction coefficientn/a
Largest diff. peak and hole1.063 and −0.491 e.Å−3
CCDC2092002
Table
Table 2. Selected bond lengths [Å] and angles [°] for compound (7m).
Table 2. Selected bond lengths [Å] and angles [°] for compound (7m).
AtomsDistanceAtomsDistance
Cl(1)-C(7)1.7480(13)N(1)-C(15)1.4555(17)
S(1)-C(1)1.7554(14)N(1)-C(14)1.4765(17)
S(1)-C(9)1.8027(14)N(1)-C(11)1.4919(16)
O(1)-C(22)1.2272(16)N(2)-C(22)1.3534(17)
O(2)-C(24)1.2169(16)N(2)-C(21)1.4052(17)
F(1)-C(28)1.3556(18)
AtomsAngleAtomsAngle
C(1)-S(1)-C(9)96.20(6)C(5)-C(6)-C(1)117.89(12)
C(15)-N(1)-C(14)119.17(11)C(5)-C(6)-C(7)122.18(12)
C(15)-N(1)-C(11)110.27(10)C(1)-C(6)-C(7)119.72(11)
C(14)-N(1)-C(11)109.32(10)C(8)-C(7)-C(6)124.07(12)
Table
Table 3. Results of cytotoxicity assay against BJ (normal), and PC3, HeLa, MCF-7, and MDA-MB231 (cancer) cell lines for the synthesized chalcones (4a-e), and spirooxindoles (7a-m).
Table 3. Results of cytotoxicity assay against BJ (normal), and PC3, HeLa, MCF-7, and MDA-MB231 (cancer) cell lines for the synthesized chalcones (4a-e), and spirooxindoles (7a-m).
CompoundsChemical Structure
4a-e/7a-m		Cancer Type/Cell Line (IC50, µM)
Human Fibroblast
BJ		Prostate PC3Cervical HeLaBreast
MCF-7		Breast
MDA-MB231
4a Symmetry 13 01426 i001NANANANANA
4b Symmetry 13 01426 i002NANA19.3 ± 0.3NANA
4c Symmetry 13 01426 i003NANA19.7 ± 0.7NANA
4d Symmetry 13 01426 i004NANANANANA
4e Symmetry 13 01426 i005NANANANANA
7a Symmetry 13 01426 i006NANA24.8 ± 0.3NANA
7b Symmetry 13 01426 i007NANANANANA
7c Symmetry 13 01426 i008NANA24.8 ± 0.2NANA
7d Symmetry 13 01426 i00911.3 ± 0.17NA12.7 ± 0.27.36 ± 0.379.44 ± 0.32
7e Symmetry 13 01426 i010NA27.5 ± 0.5NA16.45 ± 0.6121.29 ± 1.35
7f Symmetry 13 01426 i011NA8.7 ± 0.722.6 ± 0.123.27 ± 0.809.29 ± 0.34
7g Symmetry 13 01426 i012NANA10.4 ± 0.714.30 ± 0.16NA
7h Symmetry 13 01426 i013NA16.0 ± 0.725.3 ± 0.258.34 ± 0.6411.25 ± 0.28
7i Symmetry 13 01426 i014NA27.7 ± 0.9NANANA
7j Symmetry 13 01426 i015NA22.5 ± 0.412.0 ± 0.1NANA
7k Symmetry 13 01426 i01624.9 ± 0.415.6 ± 0.38.4 ± 0.526.04 ± 1.0725.28 ± 0.77
7l Symmetry 13 01426 i017NANANANANA
7m Symmetry 13 01426 i018NANA18.5 ± 0.924.16 ± 0.2521.09 ± 0.1
STD.DoxorubicinN/A1.9 ± 0.40.9 ± 0.140.79 ± 0.050.32 ± 0.002
IC50 (μM) was evaluated using MTT assay and ± is the standard deviation from three independent experiments. NA: the tested compound did not show anticancer activity at 30 µM.
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Barakat, A.; Islam, M.S.; Ali, M.; Al-Majid, A.M.; Alshahrani, S.; Alamary, A.S.; Yousuf, S.; Choudhary, M.I. Regio- and Stereoselective Synthesis of a New Series of Spirooxindole Pyrrolidine Grafted Thiochromene Scaffolds as Potential Anticancer Agents. Symmetry 2021, 13, 1426. https://doi.org/10.3390/sym13081426

AMA Style

Barakat A, Islam MS, Ali M, Al-Majid AM, Alshahrani S, Alamary AS, Yousuf S, Choudhary MI. Regio- and Stereoselective Synthesis of a New Series of Spirooxindole Pyrrolidine Grafted Thiochromene Scaffolds as Potential Anticancer Agents. Symmetry. 2021; 13(8):1426. https://doi.org/10.3390/sym13081426

Chicago/Turabian Style

Barakat, Assem, Mohammad Shahidul Islam, M. Ali, Abdullah Mohammed Al-Majid, Saeed Alshahrani, Abdullah Saleh Alamary, Sammer Yousuf, and M. Iqbal Choudhary. 2021. "Regio- and Stereoselective Synthesis of a New Series of Spirooxindole Pyrrolidine Grafted Thiochromene Scaffolds as Potential Anticancer Agents" Symmetry 13, no. 8: 1426. https://doi.org/10.3390/sym13081426

APA Style

Barakat, A., Islam, M. S., Ali, M., Al-Majid, A. M., Alshahrani, S., Alamary, A. S., Yousuf, S., & Choudhary, M. I. (2021). Regio- and Stereoselective Synthesis of a New Series of Spirooxindole Pyrrolidine Grafted Thiochromene Scaffolds as Potential Anticancer Agents. Symmetry, 13(8), 1426. https://doi.org/10.3390/sym13081426

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