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Synlett 2007(9): 1458-1460  
DOI: 10.1055/s-2007-980364
LETTER
© Georg Thieme Verlag Stuttgart · New York

A Novel Isocyanide-Based Three-Component Condensation Reaction: Synthesis of Fully Substituted Imino- and Spiroiminocyclopentenes

Ahmad Shaabani*, Ali Hossein Rezayan, Abbas Rahmati, Afshin Sarvary
Department of Chemistry, Shahid Beheshti University, P.O. Box 19396-4716, Tehran, Iran
Fax: +98(21)22431663; e-Mail: a-shaabani@cc.sbu.ac.ir;
Further Information

Publication History

Received 30 November 2006
Publication Date:
23 May 2007 (online)

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Abstract

The zwitterion formed from alkyl or aryl isocyanides and dialkyl acetylenedicarboxylate added to electron-deficient tetra­cyanoethylene or 7,7,8,8-tetracyanoquinodimethane to form fully substituted imino- or spiroiminocyclopentenes in excellent yields without using catalyst.

Key words

isocyanides - tetracyanoethylene - 7,7,8,8-tetracyanoquinodimethane - iminocyclopentene - spiroiminocyclopentene

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For a special issue on environmental chemistry, see: Chem. Rev. 1995, 95, 1-257

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Typical Procedure for the Preparation of Dimethyl 5-( tert -Butylimino)-3,3,4,4-tetracyanocyclopent-1-ene-1,2-dicarboxylate ( 4a) To a magnetically stirred solution of tetracyanoethylene (0.128 g, 1.0 mmol) and dimethylacetylenedicarboxylate (0.140 g, 1.0 mmol) in CH2Cl2 (15 mL) was added dropwise a mixture of tert-butyl isocyanide (0.83 g, 1 mmol) in CH2Cl2 (2 mL) at -10 °C over 10 min. The mixture was allowed to warm to r.t. and was stirred for 15 h. After completion of the reaction, the solvent was removed under vacuum and the residue was crystallized from CH2Cl2- n-hexane (1:2) to yield 0.353 g of 4a as a cream powder (100%); mp 161-162 °C. IR (KBr): νmax = 2256, 2207, 1739 cm-1. 1H NMR (300 MHz, CDCl3): δ = 1.56 [s, 9 H, (CH3)3C], 3.96 (s, 3 H, OCH3), 4.06 (s, 3 H, OCH3). 13C NMR (75 MHz, CDCl3): δ = 23.20 [C(CN)2], 30.16 [(CH3)3C], 46.77 [C(CN)2], 53.93 (OCH3), 54.69 (OCH3), 62.22 (CN=), 108.05 (CN), 108.75 (CN), 133.29, 139.53, 145.60 (3 signals for olefinic carbons), 158.29 (C=O), 160.26 (C=O). MS: m/z (%) = 353 (20) [MH+], 338 (25), 298 (25), 57 (100), 41 (75). Anal. Calcd for C17H15N5O4: C, 57.79; H, 4.28; N, 19.82. Found: C, 57.89; H, 4.90; N, 19.93.
Typical Procedure for the Preparation of Dimethyl 5-(2,6-Dimethylphenylimino)-4,4-dicyano-3-spiro-2-(cyclohexa-2,5-dienylidene)malononitrilecyclopent-1-ene-1,2-dicarboxylate ( 8a) To a magnetically stirred solution of 7,7,8,8-tetracyanoquinodimethane (0.204 g, 1.0 mmol) and dimethylacetylenedicarboxylate (0.140 g, 1.0 mmol) in CH2Cl2 (15 mL) was added dropwise a mixture of 2,6-dimethylphenylisocyanide (0.131 g, 1 mmol) in CH2Cl2 (2 mL) at -10 °C over 10 min. The mixture was allowed to warm to r.t. and was stirred for 24 h. After completion of the reaction, the solvent was removed under vacuum and the residue was crystallized from CH2Cl2-n-hexane (1:2) to yield 0.429 g of 8a as a brown powder (90%); mp 178 °C (dec.). IR (KBr): νmax = 2227, 1747, 1731 cm-1. 1H NMR (300 MHz, CDCl3): δ = 1.96 (s, 6 H, 2 CH3-Ar), 3.25 (s, 3 H, OCH3), 4.01 (s, 3 H, OCH3), 6.84-7.39 (m, 7 H). 13C NMR (75 MHz, CDCl3): δ = 17.75 (2 CH3-Ar), 53.27, 54.39, 60.54 [3 signals for 2 OCH3 and C(CN)2], 85.06 (C spiro), 109.78 (CN), 111.31 (CN), 125.60, 127.27, 127.87, 131.21, 136.59, 138.56, 139.65, 144.98, 146.64, 152.03, 153.47, 159.03 (C=O), 160.23 (C=O). MS: m/z (%) = 477 (30) [M+], 419 (35), 401 (30), 105 (40), 77 (100), 59 (50), 41 (20). Anal. Calcd for C27H19N5O4: C, 67.92; H, 4.01; N, 14.67. Found: C, 67.46; H, 3.87; N, 15.40.