Synthesis of 30-Bromo- and 30-Azido-20-oxo-29-nor-3β,28-diacylbetulin Derivatives

Ozonolysis of 3β,28-diacyloxylup-20,29-enes gave 20-oxo-29-nor-3β,28-diacyloxylup-20,29-enes, which were brominated with molecular bromine in AcOH to obtain a mixture of 30-bromo- and 30-dibromo derivatives. Ozonolysis of 30-bromo-3β,28-diacylbetulin produced 29-nor-30-bromoketones, whose reaction with sodium azide afforded 29-nor-30-azidoketones of the lupane...