Abstract The metalation of (E)-1-(2-chlorovinyl)-or (E)-1-(2-bromovinyl)-4-methyl-2, 6, 7- trioxabicyclo [2.2. 2] octane with tert-butyllithium produced an unsaturated homoenolate anion equivalent which intercepted alkyl halides, aldehydes, ketones, and lactones to afford β-alkylated or β-acylated orthoesters, which, in turn, furnished β-substituted acrylate esters.