Hybrid Synthesis of Optically Active Receptors Possessing Chiral Recognition Ability

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Some optically active crown ethers possessing chiral recognition ability were synthesized by using synthetic chiral building blocks as cis-1-phenylcyclohexane-1,2-diol which were prepared by the enzymatic optical resolution. Chiral recognition behavior of these crown ethers toward chiral amines was evaluated and, on the basis of the results, the mechanism of the chiral recognition behavior was examined. meso-Crown ehters which have diastereotopic faces and form diastereoisomeric complexes were prepared by using the racemic cyclohexane derivative as a steric barrier. Diastereotopic face selectivity in complexation of meso-crown ethers with achiral amines was examined.In order to obtain further informations on the mechanism of the chiral recognition, chiral crown ethers which possess the more pre-organized binding cavity were prepared and their chiral recognition abilities were studied in 1994.Our research results of the chiral recognition and diastereotopic face selectivity in complexation obtained in the three years would provide helpful informations to assist in the design of more elaborate and structured synthetic receptors.Further, stereoselectivity of lipase YS-catalyzed hydrolysis and transesterification was examined and the active site model for this lipase to identify which enantiomer of a substrate reacts faster in the reaction was reported. In 1994, stereoselectivity of transesterification mediated by lipase QL was studied and the active site model for lipase QL was also proposed. These active site models make the reactions mediated by the lipases more usefull for stereoselective organic synthesis.