2220-42-0Relevant academic research and scientific papers
Synthesis of a Novel 1α,5α-Cyclocholestane
Georghiou, Paris E.,Ren, Yi,Bridson, John N.
, p. 827 - 831 (1993)
The synthesis of 4,4-dimethyl-1α,5α-cyclocholesta-3,7-dione (11), by lithium- or ytterbium-liquid ammonia reduction of the bis-α,β-unsaturated ketone, 4,4-dimethylcholesta-1,5-diene-3,7-dione (10), is described.The chemistry of the reductive cyclization is discussed.The 1H NMR spectra of the corresponding dihydroxy derivatives of 11 reveal an unusually high-field signal due to H-9.X-ray diffraction analysis of the 7β-monool 13a indicates that ring B of the steroid nucleus is in a boat conformation and that H-9 partially eclipses the C-1-C-10 bond of the cyclopropyl ring.An anisotropic ring current effect is postulated to account for the chemical shifts of H-9 in these cyclosteroids.The chemistry of these compounds is described.
Montmorillonite clay catalysis. Part 15 backbone rearrangement of 4,4- dialkylcholest-5-enes catalyzed by montmorillonite K-10
Duan, Hui-Yun,Wang, Jian-Xin,Li, Tong-Shuang
, p. 3197 - 3205 (1999)
In the presence of montmorillonite K-10 4,4-dialkylcholest-5-enes undergo backbone rearrangement to give (20R)- and (20S)-4,4-dialkyl-5β,14β- dimethyl- 18,19-dinor-8α,9β,10α-cholest-13(17)-enes in high yields.
Synthesis and Carbon-13 Nuclear Magnetic Resonance Studies of Δ5 and Saturated 4,4-Disubstituted 3-Ketosteroids
Rizvi, Syed Q. A.,Williams, John R.
, p. 1127 - 1132 (1981)
A number of Δ5-4,4-dialkyl-3-ketosteroids were synthesized by alkylation of steroidal 4-en-3-ones via their enolate anions.Carbon-13 nuclear magnetic resonance spectra of these compounds were measured and assigned.Predicted carbon shifts show fairly good agreement with the observed values in the estrenone series.The deviations for androstenones and cholestenones were interpreted in terms of conformational changes in the steroid skeleton which arise from nonbonded 1,5-interactions (δ-effect) between the 19-methyl and the 4,4 substituents.Comparison of the carbon shifts for 4,4-dimethyl-3-ketosteroids with the appropriate Δ5derivatives did not indicate any "conformational transmission" in the latter compounds.The observed carbon shift differences for C-14 seem to arise solely from the presence of the 19-methyl group.
Montmorillonite clay catalysis. Part 31: A new ready and high yield procedure for the cleavage of acetals catalysed by montmorillonite K 10
Li, Tong-Shuang,Li, Sheng-Hui
, p. 2299 - 2303 (2007/10/03)
An easy cleavage of acetals has been carried out in excellent yield under catalysis of montmorillonite K 10 in refluxing wet acetone.
Photoinduced Transformations. Part 60. Photoinduced Rearrangements of Cholesteryl Nitrites with Monochromatic Light
Suginome, Hiroshi,Maeda, Norio,Kaji, Makoto
, p. 111 - 116 (2007/10/02)
Photolysis of cholesteryl nitrite in benzene with monochromatic light (λ 389 nm) gave (E)-4'-azodi-(3,4-secocholest-5-en-3-one) N,N'-dioxide (9) which transformed into N-hydroxy-4-aza-4a-homocholest-5-en-3-one (10) and 3,3-bisisopropoxy-3,4-secocholest-5-en-4-one oxime (20) in isopropyl alcohol under reflux.Photolysis of the dimer (9) with Pyrex-filtered light gave 3,4-secocholest-5-ene-3,4-dione 4-oxime (25).In contrast, irradiation of 4,4-dimethylcholesteryl nitrite (2) in benzene with monochromatic light gave a good yield of 4a,4a-dimethyl-4-aza-4a-homocholest-5-en-3-one (11) without any accompanying nitroso-dimers.These results as evidence that hydroxamic acids obtained from the photolysis of nitrites are formed by thermal cyclization of nitrosointermediates .Although irradiation of the nitrite (2) with Pyrex-filtered light gave a result similar to that with monochromatic light, low yields of the Z-isomer (26) of the nitroso-dimer (9) and 3β(4-oxa-4a-homocholest-5-en-3α-yloxy)cholest-5-ene (27) were isolated from a mixture obtained from the photolysis of cholesteryl nitrite (1) with Pyrex-filtered light.Some notable features in the present results are discussed.
