REGIOSELECTIVE, DIASTEREOSELECTIVE, AND ENANTIOSELECTIVE SYNTHESIS OF VIC-DIOLS VIA ALPHA-SILYL KETONES ACCORDING TO THE SAMP/RAMP HYDRAZONE METHOD

alpha-Silylated ketones 5 or 10 of high enantiomeric purity (ee greater-than-or-equal-to 90%) are easily available by silylation or silylation/alkylation of ketones 1 or 6, resp., according to the SAMP/RAMP hydrazone method. Reduction of 5 or 10 with L-selectride(R), followed by oxidative cleavage of the C - Si bond, leads to vic-diols 11 - 13 with high diastereoselectivity (de greater-than-or-equal-to 90%) and without racemization. The stereoselectivity of the reduction depends on the structure of the alpha-silyl ketones 5 or 10, the reducing reagents, and the solvents used.