Brønsted Base Catalyzed Conjugate Addition of β-Acylvinyl Anion Equivalents to α,β-Unsaturated Ketones

A Brønsted base catalyzed addition reaction of allyl sulfones having a diethoxyphosphoryloxy group, which are new precursors of β-acylvinyl anion equivalents, with α,β-unsaturated ketones was developed. The reaction proceeded efficiently under the influence of a phosphazene base as the catalyst. This is a rare example of a catalytic addition reaction of β-acylvinyl anion equivalents. A preliminary study on an asymmetric variant was also conducted with a chiral bis(guanidino)iminophosphorane catalyst.