Diastereodifferentiation in intramolecular cyclopropanations of chiral secondary allylic diazoacetates

Article abstract of DOI:10.1016/S0040-4039(98)00501-2

Intramolecular cyclopropanations of diastereomeric, secondary allylic diazoacetates were carried out in the presence of an achiral copper catalyst, Cu(TBS)₂, and the chiral rhodium catalysts Rh₂[5(S)-MEPY]₄ and Rh₂[5(R)- MEPY]₄ to give diastereomeric cyclopropyl lactones in ratios that varied with catalyst and stereochemistry of the starting material.