据报道,吡啶中的甲苯-对-磺酰氯与5α-胆甾-1-en-3β-ol(I; R = C 8 H 17)反应可直接产生1α,5-cyclo-5α-cholest-2 -烯(II)。这种重排现在显示于由C-5α被启动以氢的C-3α跨环迁移,随后的移动π的Δ的π电子1 -键,得到1α,5α桥。然后通过从C-3质子挤出完成反应,得到环类固醇(II)。通过考虑5α-氘代胆甾-1-烯-3β-醇和5α-氟胆甾-1-烯-3β-醇的溶剂分解产物已验证了该机理。
Absolute rates of bromination were measured for two series of derivatives of steroidal ketones 3, enolacetates 1 and enol methyl ether 2. Axial substituents exhibited a large effect on rates, which increased by 15,000 fold on going from (X=CH3; Y=CN) to (X=Y=H). From the bromide ion effect it was concluded that the first step (formation of an intermediate bromonium ion) was reversible and that the
测量了甾族酮3的两个系列衍生物,烯醇乙酸酯1和烯醇甲基醚2的溴化绝对速率。轴向取代基对速率表现出很大的影响,从(X = CH 3; Y = CN)变为(X = Y = H)时,轴向取代基增加了15,000倍。从溴离子效应可以得出结论,第一步(中间体溴离子的形成)是可逆的,并且第二步(卤代酮4或5或卤代缩醛8或9的形成)与第一步相比较慢。推断该中间体是高度不对称的溴离子,而不是纯的氧碳鎓离子。
<b>Optical Rotatory Dispersion Studies. LXXI.</b><sup>1</sup> <b>Halogen Atoms and the Octant Rule. The Conformations of Some 5α-Halocholestan-3-ones</b><sup>2</sup>
作者:C. S. Barnes、Carl. Djerassi
DOI:10.1021/ja00869a038
日期:1962.5
Kasal,A.; Trka,A., Collection of Czechoslovak Chemical Communications, 1974, vol. 39, p. 603 - 613
作者:Kasal,A.、Trka,A.
DOI:——
日期:——
Jacquesy,R.; Levisalles,J., Bulletin de la Societe Chimique de France, 1966, p. 1884 - 1889