I. S. Levina

Cycloaddition of diazoacetic ester to 16-dehydropregnenolone acetate under high pressure

The cycloaddition of ethyl diazoacetate to 16-dehydropregnenolone acetate under high pressure makes it possible to obtain, along with the known pyrazoline, the primary reaction product, namely the Δ1-pyrazoline.

Catalysis by lewis acids at high pressure as a method of involving hindered steroid dienophiles in the diels—Alder reaction

The joint action of Lewis acids and high pressure permits the Diels—Alder reaction to be conducted with high yields with greatly sterically hindered steroid dienophiles, which are virtually unreactive under normal conditions. The [2 + 4]-cycloadditions of dienes to Δ16-20-, Δ1-3-, Δ1,4-3-, and Δ4,6-3-ketones proceed stereospecifically with the formation of one stereoisomer for each cycloadduct. The reactions of the steroid dienes studied give mixtures of two monocycloadducts at both double bonds of the steroid, with predominance of the adduct at the sterically less-hindered double bond (Δ1- and Δ6-). The method developed is a new method of producing various modified steroids with possible hormonal or antihormonal activity.

Transformed steroids. 181. Synthesis of 16α,17α-cyclohexano-19-norprogesterone

Oxidative functionalization of the 19-angular methyl group of pregna-D6′-pentarane with its subsequent removal gave 16α,17α-cyclohexano-19-norprogesterone.

Transformed steroids 176. Reaction of Δ5-3β-substituted 16α,17α-cyclohexanopregnen-20-ones with thiols: synthesis of 3-mono- and 3,5-bis-sulfur-containing steroids

Conclusions1.The reaction of Δ5-3β-substituted pentaranes with ethanedithiol and thiophenol in the presence of BF3 etherate results in the formation of a mixture of 3-mono- and 3, 5-bisalkylthio products.2.A convenient method for the introduction of a mercapto substituent into the 3β-position of the steroid molecule was developed.

13C NMR spectra and structure of 16α, 17α-cyclohexanopregnanes with sulfur-containing substituents in rings A and B

Conclusions1.The high-resolution13C NMR spectra were analyzed for 16α, 17α-cyclohexanopregnanes substituted in rings A and B by SR (R=Ph, CH2CH2SH) and S(O)Ph groups. These spectra were used to determine the position of the double bond (Δ4 or Δ5) and the position and orientation of the 3α-SR, 3β-SR, 5α-SR, and 3β-S(O)Ph substituents.2.The α-, gb-, γ-, and δ-effects of the SR (R=Ph, CH2CH2SH) and S(O)Ph substituents on the chemical shifts of the carbon atoms of the steroid skeleton were determined and analyzed. A diastereotopic effect of the S(O)Ph group on the chemical shifts of the carbon atoms of rings A and B was discovered.

Transformed steroids. 159. D-D′-homoannelation of 20-epimeric alcohols in the pregna-D6′-pentarane series

ConclusionsA D-D′-homoannelation of 20β- and 20α-epimeric alcohols of the pregna-D6′-pentarane series with rupture of the C16-C17 and C17-C21 bonds, respectively, has been discovered.

Transformed steroids Communication 152. Photocycloaddition of 1-pentyne to 16-dehydropregnenolone acetate

ConclusionsThe regio- and stereospecific [2 + 2]-photoaddition of 1-pentyne to 16-dehydropregnenolone acetate has been used to obtain 2′-propyl-16α,17α-cyclobuteno- and cyclobutanoprogesterones.

Observance of the endo principle in the Diels-Alder reactions of A65-20-ketosteroids

ConclusionsThe condensation of 16-dehydropregnenolone acetate with piperylene at 14 kbar showed that the Diels-Alder reaction of Δ16-20-ketosteroids with butadienes at high pressure, as in the case of catalytic conditions, proceeds in accord with the endo principle for this reaction.

Transformed steroids. Communication 148. 1,3-Cycloaddition of diazomethane and diazoacetate to Δ15-17-ketoandrostane at normal and high pressures

Conclusions1,3-Cycloaddition of diazomethane and ethyl diazoacetate to Δ15-17-ketoandrostane proceeds regio- and stereospecifically from the β-region of the steroid molecule, The pyrazolinoandrostanes obtained were converted into the corresponding 15β,16β-cyclopropane derivatives.

13C NMR spectra and stereoisomerism in series of androstano-and estrano-D′-pentaranes

ConclusionsThe stereoisomerism in series of androstano- and estrano-D′-pentaranes in solution has been investigated by13C NMR. The orientation of the D′ ring in the 15α,16α-, 15β,16β-, and 15α,16β-isomers relative to the steroid skeleton, as well as the “boat” conformation of the D′ ring, were determined from the13C chemical shifts.