Template Effect of Pd(II) in the Synthesis of Differently Substituted Enantiopure γ-Butyrolactones and Its Synthetic Applications

Article abstract of DOI:10.1016/0957-4166(95)00210-G

Under the catalysis of Pd(II) in the presence of CuX2 and LiX, 1'-substituted allylic 2-alkynoates undergo stereoselective cyclization affording β, γ-disubstituted α-alkylidene-γ-butyrolactones with cis or trans relative configurations.A highly efficient hydrogenation reaction of the cyclization product afforded a trans-α, β-disubstituted-γ-butyrolactone in quantitative yield with high stereoselectivity.Isohomopilopic acid which can be converted into isopilocarpine was synthesized using this methodology by further transformation.