OXYGEN ATOM INSERTION INTO THE BENZYLIC CARBON HYDROGEN-BOND OF (R)-(-)-2-PHENYLBUTANE BY METHYL(TRIFLUOROMETHYL)DIOXIRANE - AN EFFICIENT AND MILD REGIOSELECTIVE AND STEREOSELECTIVE SYNTHESIS OF (S)-(-)-2-PHENYL-2-BUTANOL

The efficient conversion of (R)-(-)-2-phenylbutane [(-)-1] into (S)-(-)-2-phenyl-2-butanol [(-)-2] with high configurational retention was achieved under remarkably mild conditions by using methyl(trifluoromethyl)dioxirane (3a). The Arrhenius activation parameters were determined by using methyl(trifluoromethyl)dioxirane (3a) in solution of 1,1,1-trifluoropropanone (TFP) or methylene chloride. A significantly lower activation energy was determined for the oxyfunctionalization of (+/-)-1 by 3a in the less polar methylene chloride. An ordered transition state I is proposed for this regio- and stereoselective O atom insertion into the benzylic C-H bond of hydrocarbon (-)-1.