Ljudmila L. Vasiljeva

Reduction of steroidal ketones with amine—boranes

Complexes of secondary amines with borane, R2NH·BH3, surpass sodium borohydride as reducing agents for saturated and unsaturated steroidal 3-, 12-, 17-, and 20-ketones as regards chemo- and regioselectivity and mildness of the reaction conditions. In the case of 12-ketones, stereoselectivity is also improved.

Synthesis of 3β-hydroxy-androsta-5,7-dien-17-one from 3β-hydroxyandrost-5-en-17-one via microbial 7α-hydroxylation

The synthesis of 3beta-hydroxy-androsta-5,7-dien-17-one from 3beta-hydroxy-androst-5-en-17-one (dehydroepiandrosterone, DHEA) via microbial 7alpha-hydroxylation has been accomplished. At the first stage, 3beta,7alpha-dihydroxy-androst-5-en-17-one was obtained in high yield (71.2%) using a strain of Gibberella zeae VKM F-2600, which was first applied for DHEA conversion. The further route included the substitution of 7alpha-hydroxyl group with chlorine followed by a dehydrochlorination stage, and required minimal purifications of the intermediate products. The steroids obtained at every step were characterized by TLC,1H NMR, MS, UV- and IR-spectrometry. The combination of microbial and chemical steps ensured 54.6% yield of the target 3beta-hydroxy-androsta-5,7-dien-17-one from DHEA and can be applied for obtaining novel vitamin D derivatives.

Synthetic study of hepoxilins

Total synthesis of trioxilin (10S,11S,12S)-B3 was performed starting from a hepoxilin synthon, (2S,3S)-2,3-epoxyundec-5-yn-1-ol, available from the corresponding allylic alcohol by Sharpless enantiodirected epoxidation. The synthesis features stereoselective (7 ∶ 1)syn-addition of the acetylenide anion to the intermediate (2S,3S)-2,3-(isopropylidenedioxy)undec-5-yn-1-al and regioselective partial hydrogenation of a triacetylene trioxilin precursor, which allowed the preparation of 14,15-dehydro-(10S,11S,12S)-TrXB3.

Enantioselective synthesis of methyl (5Z,8S)-8,9-epoxynon-5-enoate, an eicosanoid synthon

A six-step synthesis of methyl (5Z,8S)-8,9-epoxynon-5-enoate, a known synthon of constanolactones and hepoxilins, from 5-hexynoic ester was developed. The enantiomeric purity of the synthon was attained by S-enantiodirected dihydroxylation of a double bond in the intermediate methyl non-8-en-5-ynoate with subsequent enantioselective hydrolysis of the epoxide group in the admixture of the minor R-enantiomer.

NEW SYNTHESIS OF ESTRADIOL FROM ANDROSTA-1,4-DIENE-3,17-DIONE

A new method for the aromatization of ring A in androsta-1,4-diene-3,17-dione, available from sterols by means of the microbiological degradation of the side chain, was developed. The method consists of the reduction of androsta-1,4-diene-3,17-dione to the corresponding dienediol followed by double C,O-deprotonation of ring A, accompanied by expulsion of the 19-methyl group and formation of estradiol in a high yield.

Non-selectivity in the reaction of levoglucosenone with the sulfinyl allyl carbanion

Condensation of levoglucosenone with the carbanion ofrac-allyl phenyl sulfoxide, in contrast with reactions of this anion with the majority of other unsaturated ketones, proceeds without regio- or enantioselectivity to give a (1.0–1.8): 1 mixture of products of both 1,2- and 1,4-γ-addition of the allylic residue. Each product is a (1.2–1.6): 1 mixture of epimers at the asymmetric sulfur atom.

Synthesis of tritium labelled 20-hydroxy-hepoxilin A3, the major hepoxilin metabolite in human neutrophils

Methyl (8S)-[20-3H]-8,20-dihydroxy-11,12-epoxy-5Z,9E,14Z-eicosatrienoate ((8S)-[20-3H]-20-hydroxy-HxA3 methyl ester), a radioactive analog of the HxA3 metabolite was prepared. The synthesis of the 20-hydroxy analog of HxA3 methyl ester was performed by the reduction of the corresponding 20-aldehydro-HxA3 with sodium [3H]-borohydride. The purified [20-3H]-20-hydroxy-HxA3 methyl ester had a specific activity of 2.5–2.7 Ci/mmol. Copyright