Highly chemoselective hydrogenation with retention of the epoxide function using a heterogeneous Pd/C-ethylenediamine...

In general, palladium-carbon (Pd/C) catalyzed hydrogenation of epoxides affords the corresponding primary and secondary alcohols as a mixture. It has been found that the catalytic activity of a Pd/C -ethylenediamine complex catalyst [Pd/C(en)] in the hydrogenolysis of epoxide functions is drastically reduced. Herein we describe a mild and chemoselective method for the hydrogenation of olefin, nitro, and azide functions with retention of the epoxide function. The chemoselectivity was accomplished by using a combination of 5% Pd/C(en) and THF as solvent. A significant drop in the chemoselectivity of the hydrogenation is observed with 5% Pd/C(en) in MeOH. These results reinforce the utility of epoxides as important precursors of alcohols in synthetic chemistry.