Collect. Czech. Chem. Commun. 1979, 44, 234-245

Westphalen rearrangement. Mechanism of formation of 5α-acetoxy derivatives

Pavel Kočovskýa, Václav Černýa and František Turečekb

a Institute of Organic Chemistry and Biochemistry, Czechoslovak Academy of Sciences, 166 10 Prague 6
b The J. Heyrovský Institute of Physical Chemistry and Electrochemistry, Czechoslovak Academy of Sciences, 121 38 Prague 2


5α-Acetoxy derivatives formed as by-products in the course of Westphalen rearrangement of [5-18O]-5-hydroxy-5α-cholestanes Ia and Ib are shown to preserve their 18O content. This fact rules out previously proposed neighboring group participation of the 6β-substituent involving a 5β,6β-„onium" intermediate (F).