Synthesis and conformational analysis of 3-hydroxypipecolic acid analogs via CSI-mediated stereoselective amination
作者:In Su Kim、Joa Sub Oh、Ok Pyo Zee、Young Hoon Jung
DOI:10.1016/j.tet.2007.01.028
日期:2007.3
the neighboring group effect leading to retention of stereochemistry. In addition, conformational changes of trans-piperidine intermediate 9 in terms of the nature of N-protecting groups are described. The conformations of 9 and 24–28 were confirmed by 1H NMR analysis and NOE correlation. Furthermore, the conformations of piperidines 18 and 23 with hydroxyl methyl substituent at C-2 were investigated
一种短而有效的立体选择性合成方法,涉及取代的哌啶,涉及(2 S,3 S)-3-羟基哌酸1,(2 R,3 S)-3-羟基哌酸3,以及它们的酸还原类似物2和4,已经被开发出来。必要的抗-和顺-1,2-氨基醇11和12用于制备标题四个哌啶类似物1 - 4分别通过的区域选择性和对映选择性合成胺化抗和-顺使用氯磺酰基异氰酸酯(CSI)的-1,2-二苄基醚13和14。其结果是,反应的反-1,2-二苄基醚13与CSI只得到反-1,2-氨基醇11与49的非对映选择性:1在甲苯中在-78℃和顺式-异构体14,得到以-1,2-氨基醇12为主要产物,在-78°C下在己烷中的非对映异构体选择性为12:1。这些反应的结果可以由导致立体化学保留的邻近基团效应来解释。另外,反式的构象变化就N-保护基的性质描述了-哌啶中间体9。1 H NMR分析和NOE相关性证实了9和24 – 28的构象。此外,通过NMR光谱研究了在C