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Synlett 2010(6): 955-961  
DOI: 10.1055/s-0029-1219550
LETTER
© Georg Thieme Verlag Stuttgart ˙ New York

An Easy Access to Novel Spiro-Fused Pyrrolo Benzo[b]thiophene 1,1-Dioxide Derivatives via 1,3-Dipolar Cycloaddition Using Benzo[b]thiophene 1,1-Dioxide

Neelakandan Vidhya Lakshmi, Prakasam Thirumurugan, Chinnappan Jayakumar, Paramasivan T. Perumal*
Organic Chemistry Division, Central Leather Research Institute, Adyar, Chennai 600020, India
Fax: +91(44)24911589; e-Mail: ptperumal@gmail.com;
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Publication History

Received 30 December 2009
Publication Date:
26 February 2010 (online)

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Abstract

A series of spirooxindoles containing tri- and tetracyclic fused pyrrolo benzo[b]thiophene 1,1-dioxide derivatives was synthesized regioselectively via a multicomponent 1,3-dipolar cyclo­addition of isatin, benzo[b]thiophene 1,1-dioxide and sarcosine or l-proline in methanol under reflux condition. Also a series of spiro frameworks having tri- and tetracyclic fused pyrrolo benzo[b]thiophene 1,1-dioxide derivatives was synthesized from ninhydrin, 11H-indeno[1,2-b]quinoxalin-11-one and acenaphthene-quinone using benzo[b]thiophene 1,1-dioxide as a dipolarophile. The methodology affords high yields of products in short reaction time.

Key words

spirooxindoles - azomethine ylide - multicomponent ­reaction - benzo[b]thiophene 1,1-dioxide - dipolarophile

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Crystallographic data for compound 4c in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplemental publication no. CCDC 759326. Copies of the data can be obtained, free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [fax: +44(1223)336033 or email: deposit@ccdc.cam.ac.uk].

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Typical Experimental Procedure for 4a: A mixture of isatin (1a; 1.0 mmol), sarcosine (2; 1.2 mmol), and benzo[b]thiophene 1,1-dioxide (3; 1.1 mmol) in MeOH was refluxed for 60 min and cooled to r.t. The solid formed in the reaction mixture was filtered, dried and recrystallized from EtOH to obtain the pure product in good yield (85%).
Spectral Data of Compound 4a (Table 1, Entry 1): white solid; mp 234-236 ˚C; R f 0.25 (50% EtOAc-PE). IR (KBr): 3150, 3074, 1708, 1619, 1467, 1301, 1153, 1124, 755 cm-¹. ¹H NMR (500 MHz, DMSO-d 6): δ = 1.91 (s, 3 H, Me), 3.52 (d, 1 H, J = 9.9 Hz, H1), 3.69-3.72 (m, 1 H, H2), 4.30 (t, 1 H, J = 7.6 Hz, H3), 4.53 (d, 1 H, J = 9.2 Hz, H4), 5.77 (d, 1 H, J = 7.6 Hz, ArH), 6.48 (d, 1 H, J = 8.4 Hz, ArH), 6.58 (t, 1 H, J = 7.6 Hz, ArH), 6.80 (d, 1 H, J = 7.7 Hz, ArH), 7.11 (t, 1 H, J = 7.7 Hz, ArH), 7.33 (t, 1 H, J = 7.6 Hz, ArH), 7.48 (t, 1 H, J = 7.7 Hz, ArH), 7.74 (d, 1 H, J = 7.7 Hz, ArH), 10.54 (br s, 1 H, NH, D2O exch). ¹³C NMR (125 MHz, DMSO-d 6): δ = 35.1, 52.1, 52.3, 62.1, 74.7, 110.2, 121.1, 121.5, 125.8, 127.0, 129.9, 130.1, 130.3, 132.9, 135.7, 140.3, 143.3, 179.2. MS (ESI, LCQ-MS): m/z = 341 [M + H]+. Anal. Calcd for C18H16N2O3S: C, 63.51; H, 4.74; N, 8.23. Found: C, 63.57; H, 4.72; N, 8.31.

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Typical Experimental Procedure for 12: A mixture of ninhydrin 9 (1.0 mmol), sarcosine (2; 1.2 mmol), and benzo[b]thiophene 1,1-dioxide (3; 1.1 mmol) in MeOH was refluxed for 45 min and cooled to r.t. The solid formed in the reaction mixture was filtered, dried and recrystallized from EtOH to obtain the pure product in good yield (87%).
Spectral Data of Compound 12 (Table 3, Entry 1): yellow solid; mp 252-254 ˚C; R f 0.25 (50% EtOAc-PE). IR (KBr): 1739, 1706, 1588, 1307, 1268, 1152, 1124, 768 cm-¹. ¹H NMR (500 MHz, DMSO-d 6): δ = 2.07 (s, 3 H, Me), 3.61-3.67 (m, 2 H, H1, H2), 4.35-4.37 (m, 1 H, H3), 4.72 (d, 1 H, J = 9.9 Hz, H4), 6.68 (d, 1 H, J = 7.7 Hz, ArH), 7.42 (t, 1 H, J = 6.9 Hz, ArH), 7.50 (t, 1 H, J = 7.7 Hz, ArH), 7.72 (d, 1 H, J = 7.7 Hz, ArH), 7.83 (d, 1 H, J = 7.7 Hz, ArH), 8.02-8.07 (m, 3 H, ArH). ¹³C NMR (125 MHz, DMSO-d 6): δ = 35.7, 52.1, 54.1, 61.6, 76.5, 121.7, 123.4, 123.9, 128.4, 130.5, 133.6, 134.8, 137.9, 138.1, 140.2, 140.6, 141.9, 199.3, 202.3. MS (ESI, LCQ-MS): m/z = 354 [M + H]+. Anal. Calcd for C19H15NO4S: C, 64.58; H, 4.28; N, 3.96. Found: C, 64.52; H, 4.32; N, 3.90.

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Typical Experimental Procedure for 15: A mixture of ninhydrin 9 (1.0 mmol), l-proline (6; 1.2 mmol), and benzo[b]thiophene 1,1-dioxide (3; 1.1 mmol) in MeOH was refluxed for 60 min and cooled to r.t. The solid formed in the reaction mixture was filtered, dried and recrystallized from EtOH to obtain the pure product in good yield (87%).
Spectral Data of Compound 15 (Table 3, Entry 4): yellow solid; mp 234-236 ˚C; R f 0.25 (50% EtOAc-PE). IR (KBr): 3435, 2958, 1713, 1591, 1286, 1143, 757 cm-¹. ¹H NMR (500 MHz, DMSO-d 6): δ = 1.64-1.66 (m, 1 H, CH), 1.90-1.95 (m, 1 H, CH), 2.06-2.10 (m, 1 H, CH), 2.45-2.47 (m, 1 H, CH), 2.54 (t, 1 H, J = 6.9 Hz, CH), 2.98-3.01 (m, 1 H, CH), 4.29-4.32 (m, 1 H, H3), 4.42-4.44 (m, 1 H, H1), 5.05 (d, 1 H, J = 9.9 Hz, H4), 6.60 (d, 1 H, J = 8.4 Hz, ArH), 7.33 (t, 1 H, J = 7.6 Hz, ArH), 7.44 (t, 1 H, J = 7.7 Hz, ArH), 7.69 (d, 1 H, J = 8.4 Hz, ArH), 7.77 (d, 1 H, J = 7.7 Hz, ArH), 7.98 (t, 1 H, J = 7.7 Hz, ArH), 8.03 (t, 1 H, J = 6.9 Hz, ArH), 8.13 (d, 1 H, J = 7.7 Hz, ArH). ¹³C NMR (125 MHz, DMSO-d 6): δ = 24.9, 28.9, 48.8, 50.6, 67.2, 69.2, 75.6, 122.1, 124.2, 124.7, 126.2, 130.4, 134.4, 134.8, 137.5, 138.2, 140.3, 141.4, 141.7, 196.2, 197.4. MS (ESI, LCQ-MS): m/z = 380 [M + H]+. Anal. Calcd for C21H17NO4S: C, 66.48; H, 4.52; N, 3.69. Found: C, 66.52; H, 4.58; N, 3.71.