Convergent synthesis of polyether ionophore antibiotics: synthesis of the spiroketal and tricyclic glycal segments of monensin
作者:Robert E. Ireland、Joseph D. Armstrong、Jacques Lebreton、Robert S. Meissner、Mark A. Rizzacasa
DOI:10.1021/ja00069a013
日期:1993.8
tetrahydropyranoid methylene ketone and acrolein. Finally, [6.5] - spiroketal structure II is prepared by mild acid catalyzed rearrangement of [6.6]-spiroketal epoxide 23. Glycal III was made from the C/D subunit 44. This subunit was prepared by the ester enolate Claisen rearrangement that unites the tetrahydrofuranoid C and D rings 40 and 41 by Brown crotylation, Wittig condensation, and then cyclization to form
描述了聚醚抗生素莫能菌素 (I) 的螺缩酮 II 和三环糖醛 III 部分的合成。螺缩酮 II 的丁酸侧链是通过顺式 2-丁烯醇残基的 Sharpless 环氧化或通过 α-甲基乙醛单元的布朗巴豆化来构建的。然后通过四氢吡喃亚甲基酮和丙烯醛之间的杂狄尔斯-阿尔德加成生成螺缩酮。最后,[6.5] - 螺缩酮结构 II 是通过 [6.6]-螺缩酮环氧化物 23 的温和酸催化重排制备的。Glycal III 由 C/D 亚基 44 制成。该亚基由酯烯醇化物克莱森重排制备,该亚基将四氢呋喃C和D环的40和41通过布朗巴豆基化、Wittig缩合,然后环化形成E环。