Reductive Elimination of Bromine from 1,2-Dibromoalkanes Using Organometallic Reagents

Abstract
Organocuprate(I) reagents are now being widely used for highly selective substitution reactions1 with alkyl,2 alkenyl,2 aryl,2 and acyl3 halides and with α,α'-dihaloketones.4 Organocopper interaction with 1,2-dihaloalkanes is of interest because two main reaction pathways may be expected: (a) replacement of both halogens by organic groups and (b) reductive elimination of halogen to form alkenes.5 We report here that various types of 1,2-dibromides react with lithium dialkyl-cuprate(I) reagents under exceedingly mild conditions to give alkenes exclusively (Eq. 1).