THE STEREOCHEMISTRY OF REDUCED PROAPORPHINES

Article abstract of DOI:10.1016/S0040-4020(01)81485-X

Controlled catalytic hydrogenation of the proaporphine (+)-stepharine (1) proceeded by preferential approach of the catalyst from the side opposite H-6a to provide (+)-8,9-dihydrostepharine (3), accompanied by smaller amounts of (-)-11,12-dihydrostepharine (4) and (+)-tetrahydrostepharine (5).NaBH4 reduction of 5 led to (+)-α- and (+)-β-hexahydrostepharine (6 and 7).Complete spectral and optical data were obtained for all reduction products, thus supplying reliable standards for the characterization of reduced proaporphine alkaloids.