ENANTIOSELECTIVE HYDROSILYLATION OF KETONES WITH L-ASTERISK/[RH(COD)CL]2 AND L-ASTERISK/[IR(COD)CL]2 CATALYSTS (L-ASTERISK=PH2P(O)NCH2CH(NME2)(CH2)MSME (N=0, 1, M=1,2))

The enantioselective hydrosilylation of acetophenone with diphenylsilane in the presence of L*/[Rh(COD)Cl]2 or L*/[Rh(NBD)Cl]2 (L* = Ph2P(O)nCH2CH(NMe2)(CH2)mSCH3 (n = 0, 1; m = 1, 2), COD = 1,5-cyclooctadiene, NBD = norbornadiene), followed by hydrolysis with p-toluenesulfonic acid in methanol, gave the expected sec-phenethyl alcohol in up to 62% enantiomeric excess (ee) with the (-)-(S) configuration predominating. Enantioselective hydrosilylation of acetophenone with the L*/ [Ir(COD)CI] 2 system gave up to 32% ee, but with the (+)-(R) configuration. The ee was very dependent upon the ligand L* used, but was found to be independent of the ligand to metal ratio. Enantioselective hydrosilylation of benzylacetone and alpha-tetralone followed by hydrolysis gave the (S)-alcohols in 57% and 51% ee, respectively.