Further observations concerning steroidal, β-lactones. Boron trifluoride catalysed rearrangements of β-lactones in the cholestane series

Abstract

B-Nor-5β-cholestane-3,3,5-diol-6-carboxylic acid 5,6-lactone 3-acetate on treatment with BF₃ etherate in ether or ether-acetic anhydride gave B-norcholest-5-en-3β-ol-6-carboxylic acid 3-acetate and 19-nor-5-methyl-B-nor-5β-cholest-9(10)-en-3,3-ol-6-carboxylic acid 3-acetate, a product of the Westphalen rearrangement. B-Nor-5β-cholestan-5-ol-6-carboxylic acid 5,6-lactone under similar reaction conditions provided the product of the Westphalen rearrangement, 19-nor-5-methyl-B-nor-5β-cholest-9(10)-ene-6-carboxylic acid.