Bicyclic aziridinium ions in azaheterocyclic chemistry : preparation and synthetic application of 1-azoniabicyclo[n.1.0]alkanes

Abstract

Recent advances in the field of ring-expansion chemistry, involving 1-azoniabicyclo[n.1.0]alkane scaffolds (bicyclic aziridinium ions) as key transient intermediates, have made it possible to efficiently construct a broad variety of medium-and large-sized functionalized nitrogen-containing heterocycles. In this tutorial review, a comprehensive survey of all pathways leading to the generation of 1-azoniabicyclo[n.1.0]alkanes is provided, as well as a discussion on their subsequent ring expansions to relevant azaheterocycles governed by ring size, substitution pattern, and/or nature of applied nucleophiles