Homogeneously catalysed isomerisation of allylic alcohols to carbonyl compounds

Isomerisation of allylic alcohols forms an elegant shortcut to carbonyl compounds in a completely atom-economical process that offers several useful applications in natural-product synthesis and in bulk chemical processes. This review focuses on the heart of isomerisation catalysis: the catalyst. Combinations of transition metals (from Group 4 to 10), ligands and reaction conditions are compared with respect to yield, turnovers, rate and selectivity. A selected number of clever solutions to synthetic problems are highlighted, such as the synthesis of enols and enolates, chiral carbonyl compounds and silyl substituted ketones. Furthermore, a general overview of the mechanisms proposed for the isomerisation of allylic alcohols is given while some catalyst systems are singled out to discuss mechanistic research.