Regioselective π-extension of indoles with rhodium enalcarbenoids – synthesis of substituted carbazoles?

Organic & Biomolecular Chemistry Pub Date: 2014-09-04 DOI: 10.1039/C4OB01693A

Abstract

An efficient Rh(II) carboxylate and Br?nsted acid catalyzed direct π-extension of indoles to 4-substituted carbazoles is developed. The reaction involves a regioselective C-3 functionalization of indole by a rhodium enalcarbenoid and a Br?nsted acid assisted cyclocondensation. In addition a twofold regioselective π-extension of pyrroles to 4,8-disubstituted carbazoles has also been developed. The utility of the methodology was demonstrated with the synthesis of analogues of an hepatitis C virus replication inhibitor and a secreted phospholipase A2 (sPLA2) inhibitor.

Graphical abstract: Regioselective π-extension of indoles with rhodium enalcarbenoids – synthesis of substituted carbazoles
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