Method for mild trimethylsilylation of the 14α-hydroxy group in ecdysteroids

In the reactions of poststerone derivatives and 20-hydroxyecdysone with (trifluoromethyl)trimethylsilane catalyzed by tetrabutylammonium fluoride, the 14-hydroxy group is readily subjected to trimethylsilylation.     

First Example of Trifluoromethylation in the Ecdysteroid Series. Synthesis of (20RS)-20-O-Hydro-20-trifluoromethylpoststerone

The title compound was synthesized by trifluoromethylation of poststerone derivatives with trimethyl(trifluoromethyl)silane in the presence of tetrabutylammonium fluoride.     

New method for trimethylsilylation of hydroxy-containing compounds. Synthesis of persilylated ecdysteroids and carbohydrates

A new method was developed for trimethylsilylation of alcohols by the reactions with (trifluoromethyl)trimethylsilane in the presence of tetrabutylammonium fluoride. The reactions of ecdysteroids (20-hydroxyecdysone, its 20,22-mono- and 2,3:20,22-diacetonides, and polypodine B) and carbohydrates (D-gluco-, D-galacto-, and D-xylopyranoses) afforded the corresponding persilylated derivatives.     

New Derivatives of 20-Hydroxyecdyzone. Viticosterone E Synthesis

New 20,22-mono- and 2,3:20,22-diacetals of 20-hydroxyecdyzone were synthesized, and some thereof were applied to the synthesis of 25-O-acetyl-20-hydroxyecdyzone (viticosterone E).     

Ozonolysis of Alkenes and Study of Reactions of Polyfunctional Compounds: LXVI.2* Ozonolysis and Hydrogenation of Diacetonides of 24,25- and 25,26-Anhydro-20-hydroxyecdysones. Synthesis of Ponasterone A

Ozonolysis of 2,3:20,22-diacetonides of 24.25-and 25,26-anhydro-20-hydroxyecdysones afforded the corresponding -carbonyl derivatives. The hydrogenation of the mentioned dehydration products of 20-hydroxyecdysone acetonide yielded diacetonide of ponasterone A that provided ponasterone A and its 29,22-acetonide at hydrolysis.