Synthesis 2007(24): 3851-3857  
DOI: 10.1055/s-2007-990907
PAPER
© Georg Thieme Verlag Stuttgart · New York

Synthesis of Polyalkylated Indoles Using a Thallium(III)-Mediated Ring-Contraction Reaction

Luiz F. Silva Jr.*a, Marcus V. Craveiroa, Maria T. P. Gambardellab
a Instituto de Química, Universidade de São Paulo, CP 26077, CEP 05513-970, São Paulo SP, Brazil
e-Mail: luizfsjr@iq.usp.br;
b Instituto de Química de São Carlos, Universidade de São Paulo, CP 780, CEP 13560-970, São Carlos SP, Brazil
Further Information

Publication History

Received 7 May 2007
Publication Date:
15 November 2007 (online)

Abstract

A new approach to the synthesis of cyclopenta[g]indole derivatives possessing structural features of natural alkaloids, such as trikentrins and herbindols, is described. The key step in the sequence is a thallium(III)-mediated ring-contraction reaction to transform a cyclohexene moiety into a functionalized cyclopentyl unit.

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The X-ray crystal structure data have been deposited at the Cambridge Crystallographic Data Centre and allocated the deposition number CCDC 656449. Copies of the data can be obtained free of charge on application to The Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: + 44 1223 336 033; e-mail: deposit@ccdc.cam.ac.uk).

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A complex mixture was obtained when 9 was treated with 1.1 equiv of TTN in MeOH at 0 °C.