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

A simple and practical preparation of beta-O substituted aldehydes directly from linear allylic esters is developed. Using bis(benzonitrile)palladium chloride as the catalyst and O-2 as the sole oxidant, the tandem isomerization/anti-Markovnikov oxidation reaction of linear allylic esters proceeds smoothly, giving beta-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. (BuOH)-Bu-t proved to be crucial for achieving excellent regioselectivity toward the anti-Markovnikov aldehyde products.