Rhodium-catalyzed coupling-cyclization of o-alkynyl/propargyl arylazides or o-azidoaryl acetylenic ketones with arylisocyanides: synthesis of 6H-indolo[2,3-b]quinolines, dibenzonaphthyridones and dihydrodibenzo[b,g] [1,8]-naphthyridines

Abstract

A novel rhodium-catalyzed coupling-cyclization of o-alkynyl/propargyl arylazides or o-azidoaryl acetylenic ketones with arylisocyanides has been developed. In this transformation, the reactive arylcarbodiimide intermediates generated via the coupling of o-alkynyl/propargyl arylazides or o-azidoaryl acetylenic ketones with arylisocyanides undergo intramolecular [4 + 2] cycloaddition which provides a new and simple strategy for the assembly of 6H-indolo[2,3-b]quinolines, dibenzonaphthyridones and dihydrodibenzo[b,g] [1,8]-naphthyridines in a single step from readily available non-fused ring precursors with only nitrogen as the by-product.