Conformational Analysis of the <i>cis</i>- and <i>trans</i>-Adducts of the Pictet−Spengler Reaction. Evidence for the Structural Basis for the C(1)−N(2) Scission Process in the <i>c</i><i>is</i>- to <i>trans</i>-Isomerization
作者:Dongmei Han、F. Holger Försterling、Jeffrey R. Deschamps、Damon Parrish、Xiaoxiang Liu、Wenyuan Yin、Shengming Huang、James M. Cook
DOI:10.1021/np060391g
日期:2007.1.1
The stable conformations of both the trans- and cis-1,3-disubstituted Nb-benzyl stereoisomers of the Pictet - Spengler reaction have been determined by NMR spectroscopy and X-ray crystallography in order to better understand the C(1) -N(2) cis- to trans-isomerization process. In the Na-H series, the chair conformation was preferred for the trans-isomer 3a, while the cis-isomer 3b existed predominantly
为了更好地理解C(1)-N( 2)顺式至反式异构化过程。在Na-H系列中,反式异构体3a优选椅子构象,而顺式异构体3b主要以船形存在。但是,在Na-甲基系列(1a,1b,2a,2b)中,椅子构象中同时存在顺式(1b,2b)和反式(1a,2a)非对映异构体以缓解A(1,2)应变Na-甲基官能团和C(1)上的取代基之间 Na-H和Na-甲基系列中顺式异构体的优选构象的差异(与反式异构体中的优选构象相比)可以用来理解cis-2b差向异构化为反式的速率-2a从3b变成3a。这为C(1)-N(2)分裂过程中碳正离子介导的中间体提供了结构基础。