Rhodium-Catalyzed Oxidative Cycloaddition of <i>N</i>
-<i>tert</i>
-Butoxycarbonylhydrazones with Alkynes for the Synthesis of Functionalized Pyrroles <i>via</i>
C(<i>sp</i>
<sup>3</sup>
)-H Bond Functionalization
作者:Chun-Ming Chan、Zhongyuan Zhou、Wing-Yiu Yu
DOI:10.1002/adsc.201600900
日期:2016.12.22
The reaction features a regioselective α‐imino alkyl C(sp3)−H bond functionalization resulting in selective formation of highly functionalized NH‐free pyrroles. Our studies showed that utilizing the N‐tert‐butoxycarbonyl (N‐Boc) as the oxidizing directing group is critical for achieving the observed pyrrole formation versus the isoquinoline formation. To account for the pyrrole formation, we hypothesized
铑(III)催化的的环加成ñ -叔与内部炔烃-butoxycarbonylhydrazones被开发。该反应具有区域选择性的α-亚氨基烷基C(sp 3)-H键官能化作用,可选择性地形成高度官能化的无NH吡咯。我们的研究表明,利用Ñ -叔丁氧羰基(Ñ -Boc)作为氧化剂引导组是用于实现所观察到的吡咯形成至关重要与异喹啉的形成。为了说明吡咯的形成,我们假设N在先互变异构发生苯乙hydr生成烯胺,然后进行区域选择性C(sp 2)–H裂解,形成假定的五元罗丹环。随后将罗丹环与炔烃偶联,得到吡咯产物。