J. Belmont, J. Soto, R. E. King
Sep 13, 1989
Citations
0
Influential Citations
43
Citations
Journal
Journal of the American Chemical Society
Abstract
Part I of this study describes the facile hydrogenolysis (and deuteriolysis) of alkenyl acetates, such as isopropenyl acetate (D) and 1-phenylvinyl acetate (E), with rhodacarborane catalyst precursors to yield acetic acid and the corresponding alkene. The catalyst precursors employed were (closo-3,3-(PPh{sub 3}){sub 2}-3-H-3,1,2-RhC{sub 2}B{sub 9}H{sub 11}) (I), (closo-2,2-(PPh{sub 3}){sub 2}-2-H-2,1,7-RhC{sub 2}B{sub 9}H{sub 11}) (II), and (closo-2,2-(PPh{sub 3}){sub 2}-2-H-2,1,12-RhC{sub 2}B{sub 9}H{sub 11}) (III). The hydrogenolysis of alkenyl acetates D and E produced propene and styrene, respectively, along with acetic acid in essentially quantitative yields. Deuterium at Rh was demonstrated not to enter the hydrogenolysis reaction. These results suggest a reaction mechanism for hydrogenolysis that is based upon the relatively slow formation and decomposition of a very reactive rhodium(III) monohydride formed through the regioselective oxidative addition of Rh{sup 1} (in the exo-nido tautomer of the rhodacarborane) to terminal B-H bonds. This new information predicated part II of this study, which is devoted to a modification of previously advanced proposals for the mechanisms of alkene isomerization and hydrogenation with rhodacarborane precursors.