Diastereoselective synthesis of substituted 2,3,4,5-tetrahydro-1<i>H</i>-1-benzazepine-5-carboxylic esters by a tandem reduction-reductive animation reaction
作者:Richard A. Bunce、Lara B. Johnson、Elizabeth M. Holt
DOI:10.1002/jhet.5570410413
日期:2004.7
diastereoselective synthesis of substituted and unsubstituted 2,3,4,5-tetrahydro-1H-1-benzazepine-5-carboxylic esters has been developed based on the tandem reduction-reductive amination reac tion. Catalytic hydrogenation of a series of 2-(2-nitrophenyl)-5-oxoalkanoic esters initiates a reaction sequence involving (1) reduction of the aromatic nitro group, (2) condensation of the N-hydroxylamino (or amino)
基于串联还原-还原胺化反应,已经开发了一种有效的非对映选择性合成取代的和未取代的2,3,4,5-四氢-1 H -1-苯并ze庚因-5-羧酸酯。一系列2-(2-硝基苯基)-5-氧代链烷酸酯的催化加氢引发了一个反应序列,涉及(1)芳族硝基的还原,(2)N-羟基氨基(或氨基)氮与侧链的缩合(3)还原七元环亚胺。对于具有C 2烷基和C 5酯基为顺式的产物,产生2-烷基-2,3,4,5-四氢-1 H -1-苯并pine庚因-5-羧酸酯的环化是非对映体选择。在这些反应中,环戊酸酯基团对环状亚胺中间体的还原具有很强的立体定向作用,尽管不如以前的2-烷基-1,2,3,4-四氢喹啉-4-羧酸的闭合反应所观察到的强。酯。非对映选择性的降低归因于(1)酯与亚胺双键之间的距离更大,以及(2)较大环的构象迁移率增加,这两者都减弱了酯的立体定向作用。最后,七元环的形成足够缓慢,以至于在一些反应中与侧链酯基团的反应与杂环的形成竞争。