Selective Reduction of Organic Compounds with Al-Trifluoromethanesulfonyldiisobutylalane. Comparison of Its Reactivity with Al-Methanesulfonyldiisobutylalane

The new MPV type reagent, Al-trifluoromethanesulfonyldiisobutylalane (DIBAO_3SCF_3), has been prepared and its reducing characteristics in the reduction of selected organic compounds containing representative functional groups have been examined, and compared its reactivity with that of Al-methanesulfonyldiisobutylalane (DIBAO_3SCH_3) in order to understand the fluorine-substituent effect on its reactivity. In general, the reactivity of DIBAO_3SCF_3 appears to be much higher than that of DIBAO_3SCH_3, apparently due to the acidity increase by the electron-withdrawing fluorine-substituent. The reagent reduced aldehydes and ketones readily, but showed a perfect selectivity in the reduction of α,β-unsaturated aldehydes and ketones to produce the corresponding allylic alcohols in an absolutely 100% purity. In addition, the reagent achieved the regioselective cleavage of phenyl- or/and alkyl-substituted epoxides to the less substituted alcohols in a perfect regioselectivity. Moreover, the reagent also showed an high stereoselectivity in the reduction of substituted cycloalkanones to produce the thermodynamically more stable alcohol epimers exclusively. KCI Citation Count: 5