ChemInform Abstract: 2-Vinyl-1,1,2-trihalocyclopropanes - Valuable Five Carbon Cyclopropane and Cyclopropene Synthetic Intermediates

The dichloro- and dibromocarbene adducts of chloroprene and 2,3-dichlorobutadiene are readily dehalogenated by reaction with methyllithium to give 1-halo-2-vinylcyclopropenes which on further lithium-halogen exchange give synthetically useful 1-lithio-2-vinylcyclopropenes. Trapping of 1-lithio-2-(1-chlorovinyl)cyclopropene with methyl chloroformate leads to a very unusual cyclononadienyne.