EXPLORING THE REACTIVITY OF ALKENES BEARING SILICON AND OR TIN IN THEHYDROXYL-DIRECTED HYDROGENATION - A DIASTEREOSELECTIVE SYNTHESIS OF HETEROBIMETALLIC COMPOUNDS/

The hydroxyl-directed hydrogenation of (E)- and (Z)-gamma-hydroxy viny lstannanes and silanes has been studied in the presence of (dppb)Rh(NB D)BF4 (1). Efficient routes to gamma-hydroxy stannanes and silanes hav e been developed. Diastereoselectivities from 60 to >500:1 were observ ed. A significant difference in reaction rate and pathway was observed between the (E)- and (Z)-vinylstannanes. We observed a reductive dest annation process for the (Z)-stannanes which was influenced by the siz e of the R group. Competition studies were carried out to determine if steric or electronic effects were responsible for the reactivity patt erns observed.