R. G. Savchenko

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 ω-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.

7,8-dihydro analogs of ecdysteroids

Reactions of 20-hydroxyecdysone, its diacetonide, and 24,25(25,26)-anhydro derivative with lithium tetrahydridoaluminate gave the corresponding 6α- and 6β-epimeric alcohols and 7,8-dihydro analogs.

Synthesis of 7,8α-dihydro-14α-deoxyecdysteroids.

A Pd-C-catalyzed hydrogenation in methanol and in the presence of sodium methylate is a simple, convenient and high yielding reduction method to convert the 7,14-dien-6-one ecdysteroids to their corresponding 7,8α-dihydro-14α-deoxyecdysteroids.

Stereochemistry of Hydride Reduction of 20-Hydroxyecdysone Derivatives

The 6-oxo group in 2,3:20,22-di-O-isopropylidene derivatives of 20-hydroxyecdysone and its 24,25/25,26-anhydro analog is reduced with NaBH4-CeCl3 in a stereoselective fashion to afford the corresponding 6α-alcohols. In the first case, the reaction is accompanied by dehydration to give Δ14-bond. Reduction of the same substrates with NaBH4 or LiAlH4 in the absence of CeCl3 leads to mixtures of 6α- and 6β-hydroxy derivatives, the latter prevailing. In all cases, epimerization at C5 occurs.

Regio and stereo directional oxidation of ecdysteroids and their 7,8-dihydroanalogs with ozone in pyridine

The oxidation of ecdysteroids and their 7,8-dihydroanalogs with ozone in pyridine occurred regio- and stereoselectively at the hydroxy groups of the A ring giving 2-dehydro-3α-hydroxy derivatives.

20-hydroxyecdysone oximes and their rearrangement into lactams

Abstract(E)-Oximes derived from 20-hydroxyecdysone diacetonides and 7,8-dihydro analog were converted into the corresponding lactams (6-oxo-5a-aza-5a-homo derivatives) via Beckmann rearrangement. 14,15-Anhydro-20-hydroxyecdysone (Z)-oxime under analogous conditions (reaction with p-toluenesulfonyl chloride in acetone in the presence of Na2CO3) gave rise to 20-hydroxyecdisone 20,22-acetonide (Z)-O-tosyloxime which did not undergo Beckmann rearrangement.

Hydrogenation of ecdysteroids.

Catalytic hydrogenation is extensively used in steroid chemistry. The interest in transformations to the steroid skeleton of ecdysteroids has been increasing in the past years. Essential interest in the chemistry of ecdysteroids is caused by the selective reduction of Δ7 bond with the formation of 7,8-dihydro analogues, because this process allows one to obtain modified structures with new biological activity. Catalytic hydrogenation of isolated and conjugated double bonds and functional groups in ecdysteroids derivatives has been considered in review.

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).

Hydroxylation and epimerization of ecdysteroids in alkaline media: Stereoselective synthesis of 9α-hydroxy-5α-ecdysteroids

Autoxidation of diacetonides of 20-hydroxyecdysone and ponasterone A under treatment with excess of NaOH in methanol leads to the formation of 9α-hydroxy-5α-ecdysteroids previously not described. Their structures have been determined by detailed NMR analysis. Catalytic hydrogenation (Pd-C, MeOH-MeONa) of hydroxylated ecdysteroids affords the 7,8α-dihydro-9α-hydroxy-5α-ecdysteroids.

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.