Synthesis of Naphtho[1′,2′:4,5]imidazo[1,2-<i>a</i>]pyridines and Imidazo[5,1,2-<i>cd</i>]indolizines Through Pd-Catalyzed Cycloaromatization of 2-Phenylimidazo[1,2-<i>a</i>]pyridines with Alkynes
作者:Peiyuan Li、Xinying Zhang、Xuesen Fan
DOI:10.1021/acs.joc.5b01092
日期:2015.8.7
In this paper, palladium-catalyzed oxidative cycloaromatization of 2-phenylimidazo[1,2-a]pyridine (PIP) with internal alkyne is studied. From this reaction, two classes of fused N-heterocycle, naphtho[1′,2′:4,5]imidazo[1,2-a]pyridine (NIP) and imidazo[5,1,2-cd]indolizine (IID), were formed through dehydrogenative coupling featured with cleavage of the C–H bonds located on different moiety of the PIP
本文研究了内部炔烃对钯催化的2-苯基咪唑并[1,2- a ]吡啶(PIP)的氧化环芳构化反应。从该反应中,可以得到两类稠合的N-杂环,萘并[1',2':4,5]咪唑并[1,2- a ]吡啶(NIP)和咪唑并[5,1,2- cd ]吲哚并嗪(IID )是通过脱氢偶联形成的,其特征是位于PIP底物不同部分的C–H键断裂。此外,当5-甲基-2-苯基咪唑并[1,2- a ]吡啶或2-杂咪唑并[1,2 - a使用]吡啶,可以高效获得独家产品NIP或IID。有趣的是,与Rh(III)相比,Pd(II)在促进该反应方面表现出不同的作用方式,并导致NIP的形成,其对不对称炔烃的反应具有区域选择性相反的结果。