The octant rule VIII.∗∗For paper VII, see D. A. Lightner, J. K. Gawroński and T. D. Bouman, J. Am. Chem. Soc., 102, in press. Variable temperature circular dichroism spectra of α-methyl- and methoxyl-substituted 5α-cholestan-2- and -3-ones
作者:D.A. Lightner、F.P.C. Eng
DOI:10.1016/0039-128x(80)90102-6
日期:1980.2
synthesized and their variable temperature circulardichroismspectra obtained and analyzed. Rotatory strength (R) values for alpha-axial and equatorial CH3 and OCH3 groups are determined by difference measurements with the parent ketone. The (small) equatorial CH3 R-values do not consistently follow the OctantRule. Axial OCH3 groups do not obey the OctantRule ("anti-octant" behavior) and impose a bathochromic
已经合成了2个α-和2个β-甲基和甲氧基-5α-胆甾烷-3-酮和3个α-和3个β-甲基-和甲氧基5α-胆甾烷-2-酮,并且它们的变温圆二色性获得并分析光谱。α轴和赤道CH3和OCH3基团的旋转强度(R)值是通过与母体酮的差异测量来确定的。(小)赤道CH3 R值未始终遵循八分法则。轴向OCH3基团不遵守Octant规则(“抗octant”行为),并在C = O n-pi过渡上施加红移。赤道OCH3组并非始终遵循八进制或“反八进制”行为。
Regio- and Stereospecific Synthesis of Cholesterol Derivatives and Their Hormonal Activity inCaenorhabditis elegans
作者:Arndt W. Schmidt、Thomas Doert、Sigrid Goutal、Margit Gruner、Fanny Mende、Teymuras V. Kurzchalia、Hans-Joachim Knölker
DOI:10.1002/ejoc.200600394
日期:2006.8
identified. Herein, we describe the regio- and stereospecificsynthesis of a number of cholesterol derivatives. The lithium–ammonia reduction of 4-cholesten-3-one was utilized to develop a general method for the introduction of diverse functional groups at C-4α of 5α-cholestan-3β-ol. Stereoselective functionalization at C-7 was achieved starting from 7-ketocholesterol derivatives. 6-Keto-5α-cholestan-3β-ol
The contraction of ring a in 5α-cholestane derivatives
作者:B. Fuchs、H.J.E. Loewenthal
DOI:10.1016/0040-4020(60)80070-1
日期:1960.1
The β-keto-ester which is obtained by Dieckmann cyclization of the dimethyl ester (I) of the dicarboxylic acid obtained by oxidative opening of ring A in 5α-cholestan-3-one and related compounds has been shown to have the structure IIa, by its degradation, via the unsaturated acid (Va), to A-nor-5β-cholestan-3-one (VI) and to the dimethyl ester (VIIb). The stereochemistry of compound IIa and of related
Synthetic steroids. Part X. Preparation of (3S)- and (3R)-spiro-[5α-cholestane-3,2′-oxiran] and their corresponding 2α-methyl and 2,2-dimethyl analogues
作者:J. D. Ballantine、P. J. Sykes
DOI:10.1039/j39700000731
日期:——
The preparation is reported of the 3R- and 3S-forms of spiro-[5α-cholestane-3,2′-oxiran] and their 2α-methyl and 2,2-dimethyl derivatives. The six epoxides were synthesised by addition of methylene to the relevant 3-ketone with either dimethylsulphoxonium methylide or dimethylsulphonium methylide, or by peroxidation of the corresponding 3-methylene-steroid with either m-chloroperoxybenzoic acid or