作者:Raymond Baker、Jose L. Castro
DOI:10.1039/p19900000047
日期:——
(E)-allylic alcohol (39), efficiently prepared by reaction of the aldehyde (37) with CrCl2-CH3CHI2. The remaining stereocentre at C-18 was introduced by an asymmetric hydroxylation of an enolate. Macrocyclization of the amino acid (59) to give the lactam (60) was successfully achieved by its reaction with either 2-mesitylenesulphonyl chloride or bis(2-oxo-3-oxazolidinyl)phosphinic chloride. Incorporation of
(+)-macbecin I的第一个全部对映体特异性合成是通过将环氧化物(3)与衍生自碘化乙烯(46)的高阶氰铜酸盐偶联而以收敛方式进行的。对映选择性羟醛缩合可达到C(20)–C(21)和C(12)–C(13)所需的绝对立体化学,而C(16)–C(17)的绝对立体化学可通过次级的Sharpless环氧化实现通过使醛(37)与CrCl 2 -CH 3 CHI 2反应有效地制备的(E)-烯丙醇(39)。通过烯醇盐的不对称羟基化引入C-18处剩余的立体中心。氨基酸的大环化(59)得到内酰胺(60)是通过其与2-亚甲基亚磺酰氯或双(2-氧代-3-恶唑烷基)次膦酰氯的反应而成功实现的。氨基甲酸酯官能团的引入是通过母体羟基衍生物与氰酸钠和三氟乙酸的反应实现的。用硝酸铈(IV)铵可最终氧化为醌。