Collect. Czech. Chem. Commun. 1981, 46, 2892-2897

An unusual rearrangement in hypobromous acid addition to 10β-vinyl cholestane derivatives

Pavel Kočovský and František Tureček

Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6


On treatment with hypobromous acid, 19-nor-10β-vinyl-5α-cholestan-5-ol (VIIa) rearranges to the spirocyclic ketone X. The rearrangement is postulated to proceed via the intermediate (19R)-bromonium ion VIIIa. The same reaction was observed with the methyl ether VIIb. The mechanism of the rearrangement was elucidated by 18O-labeling and product analysis.