Iron-catalysed regioselective hydrogenation of terminal epoxides to alcohols under mild conditions

The reduction of epoxides has been recognized as an important method for the synthesis of alcohols using stoichiometric amounts of metal hydride reducing agents. However, homogeneous catalysis-enabled hydrogenation processes with molecular hydrogen remain scarce. Here, we present a general methodology for the synthesis of primary alcohols in high yields, selectively and under mild conditions, from aliphatic and aromatic epoxides. Crucial for the hydrogenation of terminal epoxides is the presence of an Fe(BF4)(2)center dot 6H(2)O/tetraphos catalyst system. Compared to existing methods, which make use of noble metals, the presented protocol shows broad substrate scope and good functional group tolerance. The generality of this is showcased by transformation of various natural products, including steroids, terpenoids, sesquiterpenoids and drug derivatives, which give the desired alcohols in moderate to excellent yields. Mechanistic studies confirm the distinct feature of the catalyst system, which is active for Meinwald rearrangement of epoxides as well as for carbonyl hydrogenations.