Conjugated azomethine ylides

The 1,3-dipolar cycloaddition of azomethine ylides is an efficient and versatile tool for the construction of five-membered nitrogen-heterocycles. When the azomethine ylide is conjugated with a double bond or a 1,3-diene moiety, other reactivity pathways are also available, namely 1,5-electrocyclization or 1,7-electrocyclization. The present review is focused on the generation and reactivity of this type of dipoles, which offer general strategies for the formation of five- and seven-membered nitrogen-heterocyclic compounds. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)