A variety of optically active carboxylic esters are produced by the kinetic resolution of racemic alpha-substituted carboxylic acids using achiral alcohols, aromatic or aliphatic carboxylic anhydrides, and chiral acyl-transfer catalysts. The combination of 4-methoxybenzoic anhydride (PMBA) or pivalic anhydride with the modified benzotetramisole-type catalyst ((S)-beta-Np-BTM) is the most effective for promotion of the enantioselective coupling reaction between racemic carboxylic acids and a novel nucleophile, bis(alpha-naphthyl)methanol, to give the corresponding esters with high ee's. This protocol was successfully applied to the production of nonracemic nonsteroidal anti-inflammatory drugs from racemic compounds utilizing the transacylation process to generate the mixed anhydrides from the acid components with the suitable carboxylic anhydrides.

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The reaction pathway and the mechanism of asymmetric induction in the synthesis of (+)-trans-(1R,3R)-chrysanthemic acid methyl ester from methyl diazoacetate and 2,5-dimethyl-2,4-hexadiene in the presence of a C(1)-chiral salicylaldimine Cu(I) complex has been probed with the aid of hybrid density functional calculations. The key finding is that the alkoxycarbonyl carbene complex intermediate is intrinsically chiral and that the intramolecular hydrogen bonding in the carbene complex transmits the chirality information from the side chain to the carbene complex. Molecular orbital backgrounds of the structure of the carbene complex and the transition state of the cyclopropanation have been elucidated.