Enantio- and Diastereoselective Cyclopropanation of β,γ-Unsaturated α-Ketoester by a Chiral Phosphate/Indium(III) Complex.

We report herein an enantioselective cyclopropanation of β,γ-unsaturated α-ketoesters with diazoesters by the complexes of InBr3 and chiral calcium phosphate. The reaction proceeds via a Michael addition-cyclization pathway to afford highly functionalized chiral cyclopropanes with excellent enantioselectivities (up to >99% ee) as a single diastereoisomer.