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A number of 5,10-seco analogs of testosterone has been synthesized starting from products of the radical oxidation of 3β,17β-diacetoxy-5α-androstan-5α-ol. The obtained compounds possess a flexible 10-membered ring with substituents (O, –OH) at C-3 and C-5. Similar derivatives with an (E)- and (Z)-Δ 1(10) -double bond have been prepared also. X-ray analysis and a combination of NMR experiments...
Treatment of 3β,17β-diacetoxy-5,10-secoandrost-1(10)-en-5-one with BF 3 ·Et 2 O was shown to proceed with cleavage of the macrocycle and formation of a new compound containing a cyclopentenone ring. Based on DFT calculations, an intramolecular Lewis acid promoted [2+2]cycloaddition, followed by a cycloreversion of the intermediate oxetane, is proposed as a possible reaction mechanism.
The synthesis of a 5,10-seco steroid containing two double bonds in a AB-macrocycle as well as the preparation of a steroidal skeleton with a cyclobutane fragment is described. The structures of these compounds are different from those of natural steroids, but they are very similar with respect to conformation of the carbon skeleton.
Three new products have been isolated from the lead-tetraacetate version of the hypoiodite oxidation of 3β,17β-diacetoxy-5-hydroxy-5α-androstane. Along with the expected 1(10)-unsaturated 5,10-seco steroidal 5-ketones, the fragmentation reaction gave two epimeric C-4 iodides. Their structural assignment was based on X-ray data of one of them ((4R,10S)-4-iodo-3β,17β-diacetoxy-5,10-secoandrostan-5-one)...
A synthetic methodology for the synthesis of 13,14-seco-steroids with substituents at C-14 and C-17 is described. The approach involves Grob fragmentation of 14β-hydroxy-17β-tosylates, hydroboration-oxidation of the intermediate Δ 13(17) -olefin, and hydride reduction of the 14-ketone. An unambiguous structural assignment of (13R,14S,17S)-14,17-diacetoxy-3-methoxy-7α-methyl-13,14-secoestra-1,3,5(10)...
A number of testosterone analogs with a 13,14-secosteroidal fragment have been prepared from (13S)-13-iodo-6β-methoxy-3α, 5-cyclo-13,14-seco-5α-androstan-14,17-dione. The key steps involved stereoselective deiodination of the starting compound with triphenylphosphine and selective protection of the 17-keto group with trimethylsilylcyanide. Removal of iodine at C-13 proceeded with inversion of the...
The synthesis of 13,14-seco steroids starting from easily available (13S)-13-iodo-6β-methoxy-3α,5-cyclo-13,14-seco-5α-androsta-14,17-dione is described. The C-17 ketone was converted regioselectively into its oxime with simultaneous stereoselective deiodination at C-13. The remaining C-14 carbonyl group was then reduced stereoselectively with Ca(BH 4 ) 2 . The configurations at the...
A number of new steroidal 17-spirofuran derivatives of the 19-nor series containing Me, Et or i Pr-substituents in the heterocyclic moiety has been prepared, which are expected to have a strong progestagenic activity. The proposed approach made use of the 1-3-dipolar cycloaddition of low-molecular nitrile oxides with steroidal acetylenic alcohols followed by transformation of the isoxazole...
The synthesis of ent-19-nortestosterone from natural 19-nortestosterone is described. The synthetic sequence takes advantage of the ‘near symmetry’ properties of the steroid; removal/introduction of a methyl group and conversion of the A- into the D-ring and vice versa eventually results in overall inversion of the stereochemistry.
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