General and regioselective synthesis of substituted pyrroles by metal-catalyzed or spontaneous cycloisomerization of (Z)-(2-en-4-ynyl)amines

Bartolo Gabriele; Giuseppe Salerno; Alessia Fazio

doi:10.1021/jo034850j

General and regioselective synthesis of substituted pyrroles by metal-catalyzed or spontaneous cycloisomerization of (Z)-(2-en-4-ynyl)amines

J Org Chem. 2003 Oct 3;68(20):7853-61. doi: 10.1021/jo034850j.

Authors

Bartolo Gabriele¹, Giuseppe Salerno, Alessia Fazio

Affiliation

¹ Dipartimento di Scienze Farmaceutiche, Università della Calabria, 87036 Arcavacata di Rende, Cosenza, Italy. b.gabriele@unical.it

PMID: 14510566
DOI: 10.1021/jo034850j

Abstract

A general and regioselective synthesis of substituted pyrroles 2 by cycloisomerization of readily available (Z)-(2-en-4-ynyl)amines 1 is reported. Spontaneous cycloisomerization leading to 2 occurred in the course of preparation of enynamines bearing a terminal triple bond or a triple bond substituted with a phenyl or a CH2OTHP group. When the triple bond was substituted with an alkyl or alkenyl group, enynamines were stable and could be converted into the corresponding pyrroles by metal catalysis. CuCl2 was found to be an excellent catalyst for cycloisomerization of substrates substituted at C-3, while PdX2 in conjunction with KX (X = Cl, I) turned out to be a superior catalyst for the reaction of enynamines unsubstituted at C-3.