An efficient synthesis of nitrogen-containing heterocycles via a tandem carbenoid N-H insertion/ring-closing metathesis sequence

A series of five- to eight-membered nitrogen-containing heterocycles were prepared via a general and efficient one-pot, two-component sequence featuring rhodium-catalyzed insertion Of a vinyl-substituted alpha-diazocarbonyls into the N-H bond of a series of tert-butoxycarbonyl-(Boc)-protected amines, followed by ring-closing metathesis catalyzed by ruthenium benzylidene complexes, This methodology allows easy and convenient access to highly functionalized azacycloalkenes in moderate yields and excellent chemoselectivity in a single transformation. (C) 2009 Elsevier Ltd. All rights reserved.