Highly efficient synthesis of functionalized tertiary alcohols catalyzed by potassium alkoxide–crown ether complexes

A highly efficient Mukaiyama aldol reaction between ketones and trimethylsilyl enolates in the presence of potassium alkoxide–crown ether complexes as Lewis base catalysts (0.3–5 mol %), which minimized the competing retro-aldol reaction, was developed. These catalysts promoted other addition reactions of trimethylsilyl reagents to ketones and aldimines, such as silyltrifluoromethylation, silylcyanation, and silylphosphonylation. A direct hydrophosphonylation of ketones also proceeded when the catalysts were used as a Brønsted base under mild reaction conditions.