Syntheses of the antitumor cembrane lactones (±)-crassin (1) and (±)-isolobophytolide (2) are reported. The key steps are the titanium-induced pinacol coupling of lactone keto aldehydes 3c and 3t to yield macrocyclic diols without harming the lactone rings also present in the molecules. Compound 3t yields a diol (18a) that is converted into isolobophytolide by epoxide formation and methylenation. Compound
报道了抗肿瘤 Cembrane 内酯 (±)-crassin (1) 和 (±)-isolobophytolide (2) 的合成。关键步骤是内酯酮醛 3c 和 3t 的
钛诱导
频哪醇偶联产生大
环二醇,而不会损害分子中也存在的内酯环。化合物3t产生二醇(18a),通过
环氧化物形成和亚甲基化将其转化为异叶植物内酯。化合物 3c 生成二醇 (21a),通过羟基的双立体
化学反转、内酯化和亚甲基化将其转化为
水油素