Preparation of 3-ketodesogestrel metabolites by microbial transformation and chemical synthesis

Specific microbial reactions were used for the preparation of metabolites of 3-ketodesogestrel (13-ethyl-17β-hydroxy-11-methylene-18,19-dinor-17α-pregn-4-en-20-yn-3-one, the active form of the progestagen desogestrel. Clostridium paraputrificum transformed 3-ketodesogestrel (KDG) to the 5β-dihydro and tetrahydro metabolites 13-ethyl-17β-hydroxy-11-methylene-18,19-dinor-5β,17α-pregnan-20-yn-3-one and 13-ethyl-11-methylene-18,19-dinor-5β,17α-pregnan-20-yne-3α,17β-diol, respectively. The epimeric compound 13-ethyl-11-methylene-18,19-dinor-5β, 17α-pregnan-20-yne-3β, 17β-diol was obtained by chemical reduction of the 3-oxo compound. Mycobacterium smegmatis converted KDG to metabolites of the 5αH-series: 13-ethyl-17β-hydroxy-11-methylene-18,19-dinor-5α, 17α-pregnan-20-yn-3-one, 13-ethyl-11-methylene-18,19-dinor-5α, 17α-pregnan-20-yne-3α,17β-diol and 13-ethyl-11-methylene-18,19-dinor-5α,17α-pregnan-20-yne-3β,17β-diol. The ring A-aromatized analog of KDG 13-ethyl-11-methylene-18,19-dinor-17α-pregna-1,3,5(10)-trien-20-yne-3,17β-diol was obtained by microbial 1-dehydrogenation with Rhodococcus rhodochrous. Additionally, chemical syntheses of the microbially obtained KDG metabolites listed above were carried out. These included Birch reduction, reduction of KDG with sodium borohydride in aqueous pyridine and in methanol, reduction of KDG with potassium selectride in tetrahydrofuran, and dehydrogenation of KDG with cupric-II bromide in acetonitrile. The problems encountered in chemical syntheses favor the microbial procedures. The compounds were characterized by mass spectra (MS), IR, and circular dichroism (CD). Complete assignments of 1H and 13C chemical shifts were made using homo- and heteronuclear 2-DN-NMR spectroscopy. Chromatographic [gas-liquid chromatography (GLC), high-performance liquid chromatography (HPLC), thin-layer chromatography (TLC)] data of all the prepared KDG metabolites are presented.