Triflimide: An Overlooked High-Performance Catalyst of the Mukaiyama Aldol Reaction of Silyl Ketene Acetals with Ketones.

The Mukaiyama aldol reaction is a widely applied carbon-carbon bond forming reaction. However, despite numerous well-established methods using aldehydes as acceptors, only few examples exist with ketones. Here we report a highly practical catalytic approach to this transformation, namely, the triflimide catalyzed Mukaiyama aldol reaction of silyl ketene acetals with ketones. This method exhibits a broad substrate scope, is very rapid, tolerates functionalized substrates, and requires only parts-per-million catalyst loadings with preparative scale reactions up to hundreds of grams in excellent purity (>99 %).