5,7-Cholestadien-3 beta-ol was transformed into 14 beta-cholesta-5,7-dien-3 beta-ol in six steps. The inversion of the stereochemistry at C-14 was obtained by a selective protection of the delta 5 and the elaboration of the delta 7 double bond.
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。
5,10:13,14-Disecosteroids: novel modified steroids containing 10- and 9-membered rings
作者:Mira S. Bjelaković、Natalija M. Krstić、Nina Todorović、Aleksej Krunić、Bernard Tinant、Milan M. Dabović、Vladimir D. Pavlović
DOI:10.1016/j.tet.2009.09.066
日期:2009.11
10-secosteroids 5 and 6 with the Pb(OAc)4/I2 reagent. Complete and unambiguous 1H and 13C NMR resonance assignments of the obtained secosteroids, as well as the solution conformations of their 10- and 9-membered rings were determined by extensive analysis of 1D and 2D NMRspectral data. The structures and the solid-state conformations of 5,10-secosteroids 5–7 were confirmed by X-ray analysis. All diseco-compounds
5,7-Cholestadien-3 beta-ol was transformed into 14 beta-cholesta-5,7-dien-3 beta-ol in six steps. The inversion of the stereochemistry at C-14 was obtained by a selective protection of the delta 5 and the elaboration of the delta 7 double bond.
5,10:8,9-Disecosteroids (= Steroklastanes): A new type of modified steroids
undergo epoxidation of the C(9)=C(10) bond followed by a Baeyer-Villigeroxidation to give, as final products, the 15-membered cyclic epoxyenol lactones of type 20 and 21. The structures of the various products were determined by 1H- and 13C-NMR spectroscopy. The conformations of the 14- and 15-membered rings were established by X-ray structure analyses of 7 and 21a. A reaction mechanism for the above