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

Abstract 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 AlR 3 with a bidentate ligand, sparteine, produces dimer 1 , selectively. The complex of AlR 3 with monodentate ligand NEt 3 , 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.