Synthesis and transformations of 20-oxo-30-nortaraxasteryl acetate derivatives
摘要:
20,20-Dimethoxy-, Delta(21)-20-oxo-, and 20-oxo-30-nortaraxasteryl acetates were synthesized by selective ozonolysis of taraxasteryl acetate. Baeyer-Villiger oxidation of 20-oxo-30-nortaraxasteryl acetate with SeO2-H2O2 gave 3 beta-acetoxytaraxa-(19,20)-epsilon-lactone. Mechanism of the ozonolysis of taraxasteryl acetate is discussed. The enthalpies of formation of possible intermediates were calculated by quantum-chemical methods, and most favorable paths of the ozonolysis and dehydrogenation were determined.
Synthesis and transformations of 20-oxo-30-nortaraxasteryl acetate derivatives
摘要:
20,20-Dimethoxy-, Delta(21)-20-oxo-, and 20-oxo-30-nortaraxasteryl acetates were synthesized by selective ozonolysis of taraxasteryl acetate. Baeyer-Villiger oxidation of 20-oxo-30-nortaraxasteryl acetate with SeO2-H2O2 gave 3 beta-acetoxytaraxa-(19,20)-epsilon-lactone. Mechanism of the ozonolysis of taraxasteryl acetate is discussed. The enthalpies of formation of possible intermediates were calculated by quantum-chemical methods, and most favorable paths of the ozonolysis and dehydrogenation were determined.