Intramolecular Cyclopropanation of 1,4-Dienes through Hydroboration-Homologation: Easy Access to Bicyclo[3.1.0]hexanes

An intramolecular cyclopropanation reaction involving B-(1-chloroalkyl)catecholborane intermediates generated from 1,4-dienes through hydroboration with catecholborane and Matteson homologation was developed. This sequential procedure leading to bicyclo[3.1.0]hexanes involves the formation of three new sigma C-C bonds at the same carbon atom. A mechanistic study supports the involvement of carbocationic intermediates.