Total Synthesis of (±)-Deoxypenostatin A. Approaches to the Syntheses of Penostatins A and B
作者:Barry B. Snider、Tao Liu
DOI:10.1021/jo000850x
日期:2000.12.1
A short synthesis of (+/-)-deoxypenostatin A (28) has been carried out using the convergent coupling of dienal 11, epoxide 13, and methylenetriphenylphosphorane (17) to prepare trienol 19 in only two steps. The key step is the Yb(OTf)(3)-catalyzed intramolecular Diels-Alder reaction of hydrated trienyl glyoxylate 23, which gives lactone 24 stereoselectively. Elaboration of lactone 24 to enone 27 by
使用二烯11,环氧化物13和亚甲基三苯基磷烷(17)的会聚偶合进行了(+/-)-脱氧penostatin A(28)的简短合成,以仅两步制备三烯酚19。关键步骤是Yb(OTf)(3)催化的水合三烯基乙醛酸酯23的分子内Diels-Alder反应,这可选择性地产生内酯24。通过分子内霍纳-埃蒙斯·维蒂希反应和差向异构化将内酯24修饰成烯酮27完成了28的合成。类似地,可以从MEM醚44c中制备适量的Diels-Alder加合物45a和46a,但某些中间体的敏感性较高排除了将45a制成Penostatin A的可能性(1)。