Organometallic compound with Lewis base—IV : Dimerization of methyl crotonate by aluminum alkyl-tertiary amine complex

Aluminum alkyl-tertiary amine complex was found to induce the catalytic dimerization of methyl crotonate (MCr) to dimethyl 2-methylpent-4-ene-1,3-dicarboxylate (1) and dimethyl 2-methylpent-cis-3-ene-1,3-dicarboxylate (2). The of the γ-hydrogen of the MCr molecule. Dimer 2 is formed through the isomerization of dimer 1. The complex of AlR₃ with a bidentate ligand, sparteine, produces dimer 1, selectively. The complex of AlR₃ with monodentate ligand NEt₃, on the other hand, induces the isomerization of dimer 1 to the cis-form of dimer 2. The coordination number of aluminum alkyl-tertiary amine complex seems to control the dimerization mechanism of MCr.