An enantiospecific strategy to all four diastereomers of A-ring enyne synthon of 1<img src='/image/spc_char/alpha.gif' border=0>,25-dihydroxyvitamin D₃

Abstract

Enantiospecific syntheses of derivatives all the four diastereomers of A-ring enyne synthon of 1<img src='/image/spc_char/alpha.gif' border=0>,25-dihydroxyvitamin D₃ (5-ethynyl-4-methylcyclohex-4-en-1,3-diol) have been described starting from the abundantly available monoterpene (<i style="">R</i>)-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.