【摘要】 从豆甾醇出发,先合成了胆甾＿5＿烯＿24＿酮＿3β＿乙酸酯(2);再用过甲酸将2的5,6位双键氧化为环氧化物,后者在碱性条件下立体专一地开环得胆甾＿3β,5α,6β＿三羟基＿24＿酮(3),用醋酐将化合物3的C3＿βOH和C6＿βOH乙酰化保护后用亚硫酰氯脱水得胆甾＿4＿烯＿24＿酮基＿3β,6β＿二乙酸酯(4),4在碱性条件下脱去乙酰基得胆甾＿4＿烯＿3β,6β＿二羟基＿24＿酮(5);化合物5通过Wittig反应将C＿24羰基亚甲基化得到目标化合物24＿亚甲基胆甾＿4＿烯＿3β,6β＿二醇1,总产率为26%。合成化合物1的光谱数据与分离得到的天然物完全一致。更多还原

【Abstract】 Starting from stigmasterol, 24-methylenecholest-4-en-3β,6β-diol （1）, a cytotoxic natural hydroxylated sterol, was synthesized via 9 steps in 26% overall yield.24-keto-cholesteryl acetate （2） was prepared in five steps with an overall 64% yield.Stereopecific hydroxylation of 2 with performic acid afforded cholest-3β,5α,6β-trihydroxy-24-one （3）, followed by selective acetylation with Ac₂O/pyridine and dehydration with thionyl chloride to obtain the key intermediate cholest-4-en-24-one-3β,6β-diacetate （4）. 4 was subjected to hydrolysis using 3% KOH im MeOH to yield cholest-4-en-3β,6β-dihydroxy-24-one （5）.Finally, the target compound 1 was obtained by methylenation of 5 with triphenyl phosphonium methylide in DMSO.The physical and spectral data of 1 are completely consistent with those of the natural compound. The synthesis unambiguously confirmed the structure of the natural product 1 as 24-methylenecholest-4-en-3β,6β-diol.更多还原