A general approach to the synthesis of enantiopure 19-nor-Vitamin D3 and its C-2 phosphate analogs prepared from cyclohexadienyl sulfone

Abstract

A synthesis of enantiopure 19-nor-Vitamin D₃ and its C-2 substituted cyclic phosphate analogs is achieved via in situ trapping of an α-sulfonyl anion with a CD-ring allyl chloride and 1,2-eliminative desulfonylation exploiting the basic properties of TBAF. The A-ring is prepared via anti-selective dithiane addition to vinyl sulfone and LiBH₄ mediated sequential bis reduction of an epoxy vinyl sulfone.