Intermolecular Michael Addition of Substituted Amines to a Sugar-Derived α,β-Unsaturated Ester: Synthesis of 1-Deoxy-<scp>d</scp>-<i>g</i><i>luco</i>- and -<scp>l</scp>-<i>i</i><i>do</i>-homonojirimycin, 1-Deoxy-castanospermine and 1-Deoxy-8a-<i>epi</i>-castanospermine
作者:Nitin T. Patil、Jayant N. Tilekar、Dilip D. Dhavale
DOI:10.1021/jo0010476
日期:2001.2.1
The synthesis of polyhydroxylated piperidine alkaloids, namely, 1-deoxy-D-gluco-homonojirimycin 3a, 1-deoxy-L-ido-homonojirimycin 3b, and indolizidine alkaloids 1-deoxy-castanospermine 5a and 1-deoxy-8a-epi-castanospermine 5b, has been achieved. The key step involved is the intermolecular Michael addition of benzylamine to alpha,beta-unsaturated ester 1, derived from D-glucose, which afforded diastereomeric
多羟基化哌啶生物碱的合成,即1-脱氧-D-葡萄糖-homonojirimycin 3a,1-deoxy-L-ido-homonojirimycin 3b和吲哚并立生物碱1-deoxy-castanospermine 5a和1-deoxy-8a-ep-castanospermine 5b,已经实现。涉及的关键步骤是将分子胺在分子间的Michael加成反应中衍生自D-葡萄糖的α,β-不饱和酯1,从而得到β-氨基酯6a和6b的非对映异构体混合物,其中D-葡萄糖和L-ido-构型为C5分别。尝试增加和/或改变新生成的立体中心的非对映选择性。通过使用N-苄基氨基化锂作为迈克尔供体,在动力学控制的条件下实现了有利于L-偶合异构体6b的高立体选择性。β-氨基酯6a和6b代表目标分子的常见中间体。因此,LAH分别减少6a和6b,得到β-氨基醇7a和7b。依次氢解,氨基的选择性保护,然后水解1,2-丙酮化物