Lipase-catalyzed Stereoselective Acylation of [1,1'-Binaphthyl]-2,2′-diol and Deacylation of Its Esters in an Organic Solvent

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Abstract
A kinetic resolution of [1,12-binaphthyl]-2,2′-diol (binaphthol) and its esters was first accomplished by lipase-catalyzed transesterification in an organic solvent. Acylation of binaphthol with enol esters in diisopropyl ether-acetone (9:1, v/v) gave solely (β)-2-acyloxy-2′-hydroxy-1,r-binaphthyl (binaphthyl monoesters) having 90 ~ 95% optical purities. The unreacted binaphthol, which was also recovered in high chemical yields, was the S enantiomer with 69 — 89 % e.e. On the other hand, the lipase-catalyzed deacylation or alcoholysis of racemic binaphthyl monoesters gave (^-monoesters and (β)-binaphthol in high chemical and optical yields (>90% e.e.). In deacylation, the reaction period was much shortened by introducing the more electronegative chlorine atom into the acetyl group of the substrate.