Cyclopropanation of betulonic acid and its methyl ester with dichlorocarbene generated under phase transfer catalysis conditions

Abstract

The addition of dichlorocarbene generated under phase transfer catalysis conditions to the double bond of betulonic acid occurs stereoselectively and is accompanied by transformation of the carboxy group leading to the dichloromethyl ester and chloride of 3 oxo 20,29 (dichloromethano)lupan 28 oic acid. Together these products, the chloride of the starting betulonic acid is formed depending on the reaction conditions. The reaction of dichlorocarbene with methyl betulonate leads to the corresponding cyclopropane adduct in a quantitative yield.

Oxidative Decarboxylation of Triterpene C-28 Acids of Lupane Series

“…( 1 H-1 H COSY and 13 C-1 H correlations) of the oxidative decarboxylation products and also of compounds described earlier [5][6][7][8][9][10], allowed us to make the unambiguous and full assignment of all carbon and hydrogen atom signals in these spectra and to reveal a criterion for the determination of the stereochemistry of the C-17 atom, which are complementary. One of the criteria is the value of the chemical shift of the C-13 signal.…”