Collect. Czech. Chem. Commun. 1983, 48, 2051-2063

Electrophilic addition to the 5,6-double bond in A-nor-3,5-secosteroids

Ladislav Kohout and Alexander Kasal

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


The stereochemistry of epoxidation, Simmons-Smith methylenation and addition of bromine and hypobromous acid to 5,6-unsaturated A-nor-3,5-secosteroids was studied. The additions proceed from both sides of the molecule and, the β-oriented positively charged intermediate is regularly cleaved under participation by the substituent at C(3) to the corresponding oxa derivative II or to the lactones VI and XI. Cleavage of the cyclopropano derivative XVI with thallium(III) acetate was accompanied by Westphalen rearrangement and lead to the 5-membered lactone XXI. The structures of the products were established by spectral and chemical means and the mechanisms of reactions observed are discussed.