Ring Opening Reactions of 1,2-Didehydroprolines. Part II. Synthesis of 5-Amino-2,4-dihydroxypentanoic Acids, their 2-Piperidones and Pentanolides [1]
作者:Johannes Häusler、Hanspeter Kählig
DOI:10.1007/s00706-004-0246-y
日期:2005.5
with hydride reagents generally yields prolines together with the 2-hydroxy acids. It could be shown that the ratio of the two products depends strongly on the pH . This allowed the optimization of reaction conditions for the preparation of the target compounds (2 R ,4 R )- and (2 S ,4 R )-5-amino-2,4-dihydroxypentanoic acid. In order to separate these isomers and unambiguously assign their respective
碱性氘化氢中1,2-二氢脯氨酸的NMR光谱研究表明,氘在C-3位置的结合,可能是由于溶液中存在无环5-氨基-2-氧戊酸。用氢化物试剂还原该平衡混合物通常与2-羟基酸一起产生脯氨酸。可以证明两种产物的比例在很大程度上取决于 pH值 。这允许优化用于制备目标化合物(2 R ,4 R )-和(2 S ,4 R )-5-氨基-2,4-二羟基戊酸的反应条件。为了分离这些异构体并明确分配各自的结构,(3 R ,5 - [R )-和(3 小号 ,5 - [R )-3,5-二苯甲酰氧基-2-哌啶酮合成为通过内酰胺化和苯甲酰化的关键中间体。内酰胺也直接转化为相应的内酯。