Desymmetrization of <i>meso</i>-Cyclic Imides via Enantioselective Monohydrogenation

meso-Cyclic imides are monohydrogenated to form the corresponding hydroxy lactams in 88−97% ee using trans-[Ru((R)-BINAP)(H)2((R,R)-dpen)] and related compounds as catalysts with base in THF. The hydrogenation proceeds with high enantiogroup- and chemoselectivity, and it is a desymmetrization reaction, forming up to five stereogenic centers in one reaction. Conversion of a hydroxy lactam into the corresponding iminium ion followed by addition of indene extended the number of stereogenic centers from 5 to 7.