Synthesis of trisubstituted and tetrasubstituted alkenes via a manganate-induced migration–elimination process

Preparation of alkenes via a manganate-induced alkylation–elimination sequence was investigated. The reaction of 2-alkoxy-1,1-dibromoalkanes with trialkylmanganates afforded disubstituted or trisubstituted alkenes. Treatment of 2-alkoxy-1,1,1-tribromoalkanes with trialkylmanganates provided trisubstituted or tetrasubstituted alkenes through bromine–metal exchange, transfer of two alkyl groups from manganese to carbon, and successive elimination of metal and the β-alkoxy moieties.