Stereochemistry of the Kulinkovich Cyclopropanation of Nitriles

摘要

The stereochemistry of the Kulinkovich cyclopropanation of nitriles with alkenes has been examinedby employing (E)-disubstituted alkenes and deuterium-labeled homoallylic alcohols as a stereo-chemical probe. An intramolecular cyclopropanation proceeds with preservation of the olefinconfiguration. On the other hand, intermolecular counterparts occur with both preservation andreversal of the olefin configuration, which corresponds to retention and inversion of configuration atthe Ti-C bond, respectively, in the cyclopropane-forming step. These uncommon stereochemicaloutcomes contrast with that of the Kulinkovich cyclopropanation of tertiary amides.