H. Nemoto et al., RAPID ENANTIOSELECTIVE ACCESS TO DES-AB-TRIENIC CORTICOSTEROIDS VIA INTRAMOLECULAR CYCLOADDITION, Journal of the Chemical Society. Perkin transactions. I, (19), 1993, pp. 2237-2238
A short synthesis of an enantiomerically pure des-AB-trienic steroid 1
1 has been achieved by thermolysis of the optically active alkenic ben
zocyclobutene 9 obtained by selective nucleophilic addition of an isop
ropenyl group to the chiral epoxide 5 as a key step.