Westphalen-Lettre rearrangement

Westphalen-Lettre rearrangement. Dehydration of 5-hydroxycholesterol derivatives accompanied by C-10 to C-5 methyl migration in compounds with a (i-SLibstitucnt in C-6. 

Potassium hydrogen sulfate/acetic anhydride Westphalen-Lettre rearrangement... 

Sterols and Related Products - The Westphalen rearrangement of some JP-substituted-bp-acetoxy-5Q -hydroxycholestanes has been studied and the products and kinetics shown to be dependent on the nature of the 5-substituent. The conformations of the products were studied and in the case of the Westphalen-Lettre derivatives it was shown that ring B is in the boat conformation. The boron trifluoride catalyzed cleavage of 30 -acetoxy-4a,5-epoxy-5Ci -cholestane afforded the expected backbone rearrangement products containing a 15(17) doable bond." A similar experiment with 5Q -acetoxy-5,ba-epoxy-5o -cholestane yielded some of the rearranged derivative XW after a reaction time of 25 seconds, along with the e q)ected isomer " ... 

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