作者:Scott E. Denmark、Jeromy J. Cottell
DOI:10.1021/jo0101510
日期:2001.6.1
(+)-1-epiaustraline ((+)-1), a tetrahydroxypyrrolizidine alkaloid of the alexine/australine subclass, is described. The key step is a tandem intramolecular [4 + 2]/intermolecular [3 + 2] nitroalkene cycloaddition involving dienylsilyloxy nitroalkene 3 and chiral vinyl ether 4, which establishes four of the five stereocenters present. The final center was installed by a diastereoselective dihydroxylation
描述了高效的全合成的(+)-1-epiaustraline((+)-1),这是alexine / australine子类的四羟基吡咯烷核生物碱。关键步骤是串联的分子内[4 + 2] /分子间[3 + 2]硝基烯烃环加成反应,其中涉及二烯基甲硅烷氧基硝基烯烃3和手性乙烯基醚4,它确定了存在的五个立体中心中的四个。最终的中心是通过非对映选择性二羟基化安装的。含有甲硅烷基醚键的亚硝基缩醛甲苯磺酸盐17的氢解解掩蔽作用通过缓慢的烷基化和不希望的彼得森型消除而受到阻碍。先前通过Tamao-Fleming氧化除去硅部分的产率很高,并提供了适用于氢解和脱保护的底物。