Disulfonimides as a New Key Structure in Organocatalysis

Significance

The authors report the use of disulfonimides, such as 1, as a new catalyst class for metal-free Mukaiyama aldol reactions. Various unfunctionalized aldehydes 2 were reacted with silyl ketene acetals 3, furnishing the desired products 4 in high yields and enantioselectivities. The reactive principle is assumed to consist of an initial pre-silylation of the catalyst giving a silyl imide species, thus creating a strong Lewis acid enabling the catalytic reaction. Most probably the chirality of the products is induced through asymmetric counteranion interactions in the intermediary formed ion pairs.