Fluoride-Mediated Elimination of Allyl Sulfones: Application to the Synthesis of a 2,4-Dimethyl-A-ring Vitamin D₃ Analogue

Abstract

A coupling strategy for the synthesis of 2,4-dimethyl-1α,25­(OH)₂D₃ is achieved which involves methylation of a pro-A ring vinyl sulfone and in situ traping of the allyl sulfonyl anion with a CD ring allyl chloride. TBAF-promoted 1,2-eliminative desulfonylation and concomitant silyl ether deprotection gives the vitamin D₃ analogue