Conformational free energy differences in steroids. Part VI. Intramolecular electrostatic interactions in 3-azidocholestan-6-ones: conformational preference of the azido-group
作者:D. Neville Jones、K. J. Wyse、D. E. Kime
DOI:10.1039/j39710002763
日期:——
Equilibrations of 3α- and 3β-azido-5α-cholestan-6-ones with their 5β-isomers were influenced by intramolecular electrostatic interactions between the azide and ketone groups. Calculated values for these interactions were in reasonable accord with the experimental findings. N.m.r. spectroscopic examination of cyclohexyl azide at –80° in carbon disulphide, [2H4]methanol, and [2H8]toluene provided a value
3 Equilibrations α -和3β叠氮基-5- α与其5β异构体-胆甾-6-酮是由叠氮化物和酮基之间的分子内的静电相互作用的影响。这些相互作用的计算值与实验结果合理地吻合。在二硫化碳,[ 2 H 4 ]甲醇和[ 2 H 8 ]甲苯中于–80°进行环己基叠氮化物的Nmr光谱检查,可为叠氮基的构象偏爱度提供一个值。对于2 M,最准确的数字是0·80±0·06 kcal mol –1-二硫化碳溶液。讨论了叠氮基,异氰酸根基和异硫氰酸根基的构象偏好之间的差异。
Isolation of Plakinamine I: A New Steroidal Alkaloid from the Marine SpongeCorticiumsp. and Synthesis of an Analogue Model Compound
A new cytotoxic steroidal alkaloid, plakinamine I, with an unprecedented 3α-amino-19-acetoxy nucleus was isolated from a Corticium sp. sponge. The structure has been elucidated by spectroscopic analysis and secured by the synthesis of the model 19-acetoxy-3α-aminocholestane. The evaluation of the cytotoxic activities of several synthetic derivatives, intermediates of the above synthesis, allowed us