Catalytic asymmetric Simmons-Smith cyclopropanation of silyl enol ethers. Efficient synthesis of optically active cyclopropanol derivatives

reaction: see text] This paper describes a catalytic asymmetric Simmons-Smith cyclopropanation of silyl enol ethers using dipeptide 2 as the ligand. A variety of optically active cyclopropyl silyl ethers can be obtained in high yields. Up to 96% ee was obtained. The dipeptide can be recovered after the reaction in good yield and reused without the loss of reactivity or enantioselectivity.