An enantiospecific strategy to all four diastereomers of A-ring enyne synthon of 1alpha,25-dihydroxyvitamin D_3

摘要

Enantiospecific syntheses of derivatives all the four diastereomers of A-ring enyne synthon of 1alpha,25-dihydroxyvitamin D_3 (5-ethynyl-4-methylcyclohex-4-en-1,3-diol) have been described starting from the abundantly available monoterpene (R)-carvone,exploiting the isopropenyl group of carvone as an equivalent of an hydroxy group.A combination of Criegee rearrangement and Mitsunobu reactions has been strategically employed.