Diazo‐Based Construction of Heterocyclic Systems Via a X−H Insertion/Cyclization Cascade

Abstract The X−H insertion reaction (X=heteroatom) of diazo compounds has emerged as an eminent and reliant approach for the construction of C−X bonds. By merging X−H insertion with the sequential ring‐closing transformations, diverse heterocyclic systems can be obtained in a step‐economical manner. In recent years, the X−H insertion/cyclization cascades and one‐pot transformations attract more research attention, especially in the area of asymmetric synthesis. Concentrating on the assembly of N,O,S‐heterocycles, this Concept elucidates the various combinations of X−H insertion reactions with cyclization via an addition to multiple bonds. The ring‐forming strategies reviewed comprise of Michael‐type and Conia‐ene reactions, aldol condensation, and Mannich reaction.