The oxidative decarboxylation of betulonic, 3,20-dioxo-29-nor-lupan-28-oic, dihydrobetulonic acids with Pb(OAc)4 in the presence of Py, Cu(OAc)2, CF3COOH or with PhI(OAc)2 – I2 leads to 28-nor-lup-16(17)-enes and 28-nor-lup-17(22)-enes, and 17α-acetoxy derivatives. The proportion of regioisomeric olefines is related to a substituent at C-19; the yields of olefines and of acetoxy derivatives depends on reaction conditions and structures of the starting acids. The structures of products were determined by spectroscopic methods.
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