One-Pot Tandem Amidation, Knoevenagel Condensation, and Palladium-Catalyzed Wacker Type Oxidation/C–O Coupling: Synthesis of Chromeno-Annulated Imidazopyridines
作者:Khima Pandey、Krishnan Rangan、Anil Kumar
DOI:10.1021/acs.joc.8b00884
日期:2018.8.3
direct one-pot synthesis of chromeno-annulated imidazo[1,2-a]pyridines is achieved by the reaction of 2-amino-1-(2-ethoxy-2-oxoethyl)pyridinium salts with 2-bromoarylaldehydes using Pd(TFA)2 as a catalyst and Cu(OAc)2 as an oxidant. The overall strategy involves tandem base-mediated amidation and Knoevenagel condensation, followed by palladium-catalyzed Wacker type oxidation and intramolecular C–O coupling
通过使用Pd(TFA)使2-氨基-1-(2-乙氧基-2-氧乙基)吡啶鎓盐与2-溴芳基醛反应,可直接合成一氧化铬修饰的咪唑并[1,2- a ]吡啶)2作为催化剂,Cu(OAc)2作为氧化剂。总体策略涉及串联碱基介导的酰胺化和Knoevenagel缩合,然后进行钯催化的Wacker型氧化和分子内C–O偶联反应。该方法简单,耐受不同的官能团,并给出中等程度到良好的产色量[2',3':4,5]咪唑并[1,2 - a ]吡啶-12-衍生物。发达的串联反应也成功地用于合成吡喃并稠合的咪唑并[1,2- a]。通过使用3-溴-3-芳基丙烯醛制备]吡啶。