Asymmetric construction of benzylic quaternary carbons from chiral malonates: Formal synthesis of natural (-)aphanorphine

Article abstract of DOI:10.1016/0957-4166(95)00097-9

Enantiomerically pure (+)-dihydronaphthalene 4, a precursor of (-)-aphanorphine, was obtained from the homochiral malonic acid ester (R)-(+)-5, via the chiral lactone (+)-12 prepared by a Wittig-Horner reaction and hydrogenation, which underwent subsequent acidic Friede-Crafts cyclisation.