The reaction of silyl enol ethers which are stable and isolable carbon nucleophiles with activated carbonyl com- pounds is one of the most versatile synthetic tools for the car- bon-carbon bond formation.1 Although Lewis acids such as TiCl4, SnCl4, BF3·OEt2, etc. are frequently employed in these reactions as useful promoters, it is still strongly desired to explore a new and effective catalyst which accelerates the reac- tions under essentially neutral conditions. Previously, ...
