Diastereodivergent Pictet-Spengler Cyclization of Bicyclic<i>N</i>-Acyliminium Ions: Controlling a Quaternary Stereocenter
作者:Benoît de Carné-Carnavalet、Jean-Philippe Krieger、Benoît Folléas、Jean-Louis Brayer、Jean-Pierre Demoute、Christophe Meyer、Janine Cossy
DOI:10.1002/ejoc.201403469
日期:2015.2
of the Pictet–Spengler cyclization of bicyclic N-acyliminium ions that contain a 3-azabicyclo[n.3.0]alkane core and an electron-rich π-nucleophilic moiety, such as an indol-2-yl, indol-3-yl, 1-methylpyrrol-2-yl, or 3,5-dimethoxyphenyl group, was examined. The N-acyliminium ions were generated by protonation of the corresponding enamides or hemiaminals, which were derived from imides. Control of the
双环 N-acyliminium 离子的 Pictet-Spengler 环化的非对映选择性,该离子包含 3-氮杂双环 [n.3.0] 烷烃核心和富含电子的 π-亲核部分,例如 indol-2-yl、indol-3-检查了基、1-甲基吡咯-2-基或3,5-二甲氧基苯基。N-acyliminium 离子是通过相应的烯酰胺或半胺的质子化产生的,它们来自酰亚胺。通过微调反应条件,以非对映发散的方式控制在新形成的环结处产生的四元立体中心,这决定了反应是在动力学还是热力学控制下进行。机理研究表明,在平衡过程中涉及逆向 Pictet-Spengler 反应途径。