Different kinetic rate laws were observed for two diastereomeric catalysts which separately gave opposite enantioselectivities in the asymmetric hydrogenation of the dimethyl ester of itaconic acid. In reactions carried out using an equal mixture of the two catalysts, a conversion-dependent enantioselectivity was predicted from the separate reaction-rate data, in agreement with the experimentally observed final enantioselectivity of 54.8 % ee (see diagram).

Efficient catalysis of asymmetric hydrogenations is possible with complexes of the type 1 which contain chiral diphosphites as ligands. Thus the Rh‐catalyzed hydrogenation of dimethyl itaconate with a catalyst containing 1,4:3,6‐dianhydro‐D‐mannite and conformationally enantiomeric diols is highly enantioselective.

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