Synthesis of Steroid Phosphates via Monomeric Metaphosphate

Article abstract of DOI:10.1021/jo00157a005

Dihydrogen phosphate esters derived from steroids having one, two, and three conjugated or nonconjugated double bonds have been conveniently prepared by a procedure that probably involves the monomeric metaphosphate anion as an intermediate.The source of metaphosphate is a 1:2 molar mixture of (1-phenyl-1,2-dibromoethyl)phosphonic acid and diisopropylethylamine (B) in a 0.05 M dichloromethane solution at 20 deg C: (1) C6H5C(Br)(PO3H2)CH2Br + 2B + ROH -> ROPO3H(-)BH(+) + C6H5CBr=CH2 + Br(-)BH(+); (2) ROPO3H(-)BH(+) + HCl -> ROPO3H2 + BH(+)Cl(-).Yields of steroid dihydrogen phosphates with on e or two double bonds range from 65percent to 75percent.The labile Δ^5,7,9-cholestatriene 3β-O-phosphate can be isolated in a pure state, although in lower yield (46percent), by this procedure.