Biomimetic total synthesis of steroids X. Synthesis of 7-(methoxymethyl)- and 7-(phenylmethoxymethyl)-19-norsteroids
作者:M. B. Groen、F. J. Zeelen
DOI:10.1002/recl.19861051206
日期:——
Cationic cyclization of 2-[6-(m-methoxyphenyl)-5-(methoxymethyl)-(E)-3-hexenyl]-3- methyl-2-cyclopentenol 23a and of the phenylmethoxymethyl analogue 23b has been studied. Although oxygen participation with the cyclization by the ether group is possible, and was observed, cyclization to steroids remains the major pathway.
Biomimetic total synthesis of steroids VIII. Stereospecific synthesis of B-homo-19-norsteroids
作者:M. B. Groen、F. J. Zeelen
DOI:10.1002/recl.19841030505
日期:——
13(17)-gonatetraene (9), was converted in two steps into B-homoestrone methylether 20. High-resolution 1H NMR spectra indicated that the seven-membered ring in 9 occurs mainly in a boat-like conformation whereas in its 1-methoxy isomer 8 it occurs in an unsymmetrical twist-boat conformation. In 20, the B-ring probably occurs both in chair and boat conformations.
2- [7-(3-甲氧基苯基)-(E)-3-庚烯基] -3-甲基-2-环戊烯醇(7)的阳离子环化主要通过Ar 1 -6和/或Ar 2 -7参与产生四环产物。主要产物,3-甲氧基-17-甲基-乙-homo -1,3,5(10),13(17)-gonatetraene(9),转化在两个步骤中进乙-homoestrone甲基醚20。高分辨率的1 H NMR光谱表明,9中的七元环主要以船形构象出现,而其1-甲氧基异构体8则以不对称的扭曲船构象出现。在20中,乙-ring可能同时出现在椅子和船上。