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-potsynthesis 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。
Selective synthesis of some imidazopyridine-fused chromones
作者:Marta Costa、M. Fernanda Proença
DOI:10.1016/j.tet.2011.09.054
日期:2011.11
A fused heterocyclic scaffold combining the imidazo[1,2-a]pyridine with a substituted chromone was synthesized in a one-pot procedure. The reaction proceeds by intramolecular cyclization of 1-(2-imino-2H-chromen-3-yl)pyridinium chloride in ethanol and in the presence of DABCO. A detailed study of the experimental conditions allowed a clear understanding of the reaction pathway.
通过一锅法合成了结合有咪唑并[1,2- a ]吡啶和取代的色酮的稠合杂环支架。该反应通过在乙醇中和在DABCO存在下将1-(2-亚氨基-2 H-铬-3-基)吡啶鎓氯化物进行分子内环化而进行。对实验条件的详细研究可以清楚地了解反应途径。