2-Hetero-cholestanes

2-oxa (11), 2-thia (12) and 2-aza (19), 5α-cholestanes were prepared from the sulfonic esters of A-seco-2-nor-5α-cholestan-1,3-diol (9 and 10). Although cyclopentamethylenediphenylphosphonium tosylate (4) could be obtained from pentan-α,ω-ditosyloxy (6) and Ph₂PK, attempts to prepare 3-phosphacholestane (16) in a similar fashion from 9 or 10, yielded only A-seco-2-nor 5α-cholestan-1-tosyloxy-3-diphenylphosphine (17).