New Aspects of Catalytic Intramolecular C−H Amination: Unexpected Formation of a Seven-Membered Ring in Nitrogen-Containing Systems

The first example of the formation of a seven-membered ring by way of intramolecular-catalyzed amination of saturated C−H bonds is reported (Du Bois reaction). The influence of various structural parameters was studied, and it was shown that the unexpected regioselectivity observed in nitrogen-containing systems could be rationalized by conformational factors. These results open the way to innovative strategies for the general synthesis of polyfunctionalized piperidines.本研究报道了首例通过饱和碳氢键（saturated C−H bonds）分子内催化胺化反应（intramolecular-catalyzed amination）构建七元环（seven-membered ring）的实例，即杜博伊斯反应（Du Bois reaction）。研究考察了多种结构参数对反应的影响，结果证实，含氮体系中观测到的反常区域选择性（regioselectivity）可通过构象因素（conformational factors）得到合理解释。上述研究成果为多官能团化哌啶（polyfunctionalized piperidines）的通用合成开辟了创新性策略的发展路径。