Synthesis and Conformational Analysis of the Multidrug Resistance-Reversing Agent Hapalosin and Its Non-<i>N</i>-methyl Analog
作者:Tam Q. Dinh、Xiaohui Du、Robert W. Armstrong
DOI:10.1021/jo9608329
日期:1996.1.1
Hapalosin was initially synthesized by macrolactonization, and a second synthesis was achieved by cycloamidation. In both syntheses, three of the five stereocenters in hapalosin were established by two Brown allylboration reactions. The synthesis of the non-N-Me analog of hapalosin involved chelation-controlled reduction of a gamma-amino-beta-keto ester and cycloamidation. In CDCl(3) at 25 degrees
Hapalosin最初是通过大内酯化合成的,第二个合成是通过环酰胺化实现的。在两个合成中,通过两个布朗烯丙基硼化反应建立了哈帕辛中五个立体中心中的三个。碱性磷酸酶的非N-Me类似物的合成涉及螯合控制的γ-氨基-β-酮酸酯的还原和环酰胺化。在25摄氏度的CDCl(3)中,合成的哈波辛以构象异构体的2.3:1混合物形式存在,而其非N-Me类似物仅以一个构象异构体形式存在。(1)H,(1)H-NOESY和计算表明,酰胺键的构型负责这两种化合物的构象。发现碱性磷酸酶的主要构象体是s-顺式酰胺,次要构象体是s-反式酰胺,非N-Me类似物是s-反式酰胺。将距离约束应用于表现出NOESY相关性的质子,计算表明,碱性磷酸酶的主要构象物和非N-Me类似物具有非常不同的构象。相比之下,Hapalosin的次要构象者和非N-Me类似物具有非常相似的构象。