Catalytic Asymmetric Intramolecular Cyclopropanation of α-Diazo-α-Silyl Acetate

Abstract

The catalytic asymmetric intramolecular cyclopropanation (CAIMCP) of α-diazo-α-silyl acetates to form oxabicyclo[3.2.1]hexane, which proceeds with high yields and enantioselectivities, is described. The maximum enantiomeric excess observed was 96% ee and the absolute configuration of the products was elucidated. The counteranion of the Cu(I) catalyst was found to play a crucial role in determining the yields and enantioselectivities, with highly anionic counteranions improving both yields and enantioselectivities. Our previously reported model explains the enantiofacial selectivity of the reacting alkene.

Key words

asymmetric catalysis - cyclopropanation - diazo compounds - enantioselectivity - lactones

• References and Notes

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