Direct synthesis of β-acyloxy aldehydes from linear allylic esters using O2 as the sole oxidant

Abstract

A simple and practical preparation of β-O substituted aldehydes directly from linear allylic esters is developed. Using bis(benzonitrile)palladium chloride as the catalyst and O₂ as the sole oxidant, the tandem isomerization/anti-Markovnikov oxidation reaction of linear allylic esters proceeds smoothly, giving β-acyloxy aldehydes as products. This method shows a broad substrate scope and a variety of allylic alcohol derivatives bearing tertiary and even quaternary carbon centres can be selectively converted to the corresponding products. ^tBuOH proved to be crucial for achieving excellent regioselectivity toward the anti-Markovnikov aldehyde products.