Chemistry of gem-dihalocyclopropanes VIII A convenient preparation of gem-dibromocyclopropanes

✍ Scribed by L. Skattebøl; G. Aziz Abskharoun; T. Greibrokk

• Publisher: Elsevier Science
• Year: 1973
• Tongue: French
• Weight: 171 KB
• Volume: 14
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)95945-3

✦ Synopsis

The method described by Makosza and Wawrzyniewicz 1,2,3 is a most useful addition to the arsenal of dihalocarbene-generating reactions4. The two-phase reaction system consisting of the olefins, chloroform, and 50% aqueous sodium hydroxide with a tetraalkylammonium chloride as catalyst provides a particularly reactive dichlorocarbeneL'J that results in high yields og gem-dichlorocyclopropanes. It has been reported2 that the exchange of chloroform with bromoform resulted in poor yields of the corresponding gem-dibromocyclopropanes. Depending on the structure, the latter can be con-5 verted with alkyllithium into allenes , bicyclobutanes6 and other strained hydrocarbons'. These reactions would be the more valuable from a preparative point of view if the starting material could be prepared by the Makosza method, and in the present communication we want to report that under the proper conditions good yields of gem-dibromocyclopropanes were obtained from various olefins by that procedure.