摘要：

A chiral alkanoic acid was prepared with up to 52% excess of the (S) enantiomer by hydrogenating an α,β -unsaturated carboxylic acid with a cinchonidine-Pd/Al 2 O 3 catalyst system. Favourable conditions are: high surface hydrogen concentration ( 60 bar hydrogen pressure, low catalyst concentration and apolar solvents), near ambient temperature and a cinchonidine/reactantmolar ratio of at least 0.4 mol%. It is proposed that high hydrogen solubility and the presence of 2-methyl-2-pentenoic acid reactant as dimers are advantageous for enantiodifferentiation.

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