induced HgO/I2 oxidation of cholest-5-en-3α-ol (6) and cholest-5-en-3β-ol (7) afforded (Scheme 3) products arising from the corresponding alkoxy radicals (12, 13 and 14a,b) and from attack of the I2O intermediate at the olefinic double bond (epoxides 15a and 16a,b respectively). With cholest-5-ene-1α,3β-diol 3-acetate (8) and cholest-7-ene-3β,5α-diol 3-acetate (9) the HgO/I2 oxidation led to unresolvable
胆甾-5-烯-3α-醇(6)和胆甾-5-烯-3β-醇(7)的光化学诱导HgO / I 2氧化提供(方案3)相应的烷氧基自由基(12、13和14a,b)和I 2 O中间体在烯烃双键(分别为环氧化物15a和16a,b)上的侵蚀。使用胆甾5-烯-1α,3β-二醇3-乙酸盐(8)和胆甾7-烯-3β,5α-二醇3-乙酸盐(9),HgO / I 2氧化导致无法分离的复杂混合物(方案5 )。使用相同的试剂cholest-5-en-3α-ol乙酸酯(10)和cholest-5-en-3β-ol乙酸酯(11)仅受到I 2 O的攻击,生成环氧化物20a,b,碘醇21以及重排产物19和22(方案7)(对于10而言),主要是环氧化物23a,b(方案8)的11。
Tetramethyldiamidophosphoric acid chloride mediated epoxide–diene conversion and steroidal aromatization
作者:Ayhan S Demir
DOI:10.1016/s0040-4020(00)01002-4
日期:2001.1
open chain and cyclic epoxides. A C–C bond cleavage reaction occurs if the epoxide contains a quaternary carbon. Application of this method to epoxy sterols afforded ring A aromatic steroids in good yield. The aromatization works via dienol-benzene rearrangements and is independent of the C-3 stereochemistry.
A general catalytic and environmentally friendly method for beta-epoxidation of Delta(5)-unsaturated steroids has been developed, which uses ketones as the catalysts and Oxone as the terminal oxidant. A whole range of Delta(5)-unsaturated steroids, which bear different functional groups such as hydroxyl, carbonyl, acetyl, or ketal, as well as different side chains, were conveniently converted to the corresponding synthetically and biologically interesting 5 beta,5 beta-epoxides with excellent beta-selectivities and high yields.
Holland, Herbert L.; Jahangir, Canadian Journal of Chemistry, 1983, vol. 61, p. 2165 - 2170