Conjugate addition to the acrylic acid moiety of artemisinic acid 2 was made possible by in situ protection as a silyl ester followed by treatment with a trimethylsilylmethyl cuprate such as (TMSCH2)C4H9CuLi•LiX, where X = CN or I. After deprotective workup, the homologated carboxylic acid 9 was obtained in excellent yields. Photoxygenation and acid treatment of 9 then led to the facile preparation of potent 9β-modified analogs of the naturally occurring antimalarial agent, artemisinin.
通过
硅酯原位保护,然后用三甲基
硅甲基
铜酸盐(如 (TMSCH2)C4H9CuLi-LiX,其中 X = CN 或 I)进行处理,
青蒿素酸 2 的
丙烯酸分子就可以实现共轭加成。然后对 9 进行光氧合和酸处理,就能轻松制备出天然
抗疟药青蒿素的强效 9δ-修饰类似物。