Asymmetric Diels-Alder reaction prostaglandin synthesis

Asymmetric Diels-Alder reactions. The acrylate of (+ )-l is markedly superior to ( —)-menthyl acrylate in effecting asymmetric induction in Diels-Alder reaction with cyclopentadiene (Lewis acid catalysis, equation I). A chiral intermediate in Corey s prostaglandin synthesis was obtained by the reaction of (-1- )-8-phenylmenthyl acrylate with a cyclopentadiene derivative.1... 

Compound 168 is a key intermediate for the synthesis of prostaglandin or prostacyclin compounds. Scheme 5-50 shows its preparation via a retro Diels-Alder reaction and subsequent treatment. Using enzyme-catalyzed acetylation, Liu et al.80 succeeded in the asymmetric synthesis of enantiomerically pure (+)/ (—)-156 and (—)-168 from the meso-Aio 164. When treated with vinyl acetate, meso-diol 164 can be selectively acetylated to give (+)-165 in the presence of Candida cyclindracea lipase (CCL). The yield for the reaction is 81%, and the enantiomeric excess of the product is 98.3%. 

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