Synthesis of Imidazo[1,2-a]pyridines by the Bis(acetyloxy)(phenyl)-λ³-iodane-Mediated Oxidative Coupling of 2-Aminopyridines with β-Keto Esters and 1,3-Diones
作者:Wei Yu、Xianpei Wang、Lijuan Ma
DOI:10.1055/s-0030-1260106
日期:2011.8
2-aminopyridines and β-keto esters by using bis(acetyloxy)(phenyl)-λ³-iodane as an oxidant and borontrifluoride etherate as a catalyst. The amount of catalyst plays a key role in determining the course of the reaction. Whereas the use of 0.2 equivalents of catalyst ensures the generation of imidazo[1,2-a]pyridines, raising the amount of catalyst to 1.0 equivalents results in exclusive α-acetoxylation of
咪唑并[1,2一]吡啶-3-羧酸盐,可直接由2-氨基吡啶和β酮酯通过使用双(乙酰基氧基)制备(苯基)-λ ³ -iodane作为氧化剂和三氟化硼醚作为催化剂。催化剂的量在确定反应过程中起关键作用。尽管使用0.2当量的催化剂可确保生成咪唑并[1,2- a ]吡啶,但将催化剂的量提高至1.0当量可导致β-酮酯的独家α-乙酰氧基化。2-氨基吡啶也可以与1,3-二酮反应,得到3-酰基咪唑并[1,2- a ]吡啶。 杂环-多环-环化-氧化-偶联
NBS mediated one-pot regioselective synthesis of 2,3-disubstituted imidazo[1,2- a ]pyridines and their unambiguous characterization through 2D NMR and X-ray crystallography
作者:Ranjana Aggarwal、Gulshan Singh、Dionisia Sanz、Rosa M. Claramunt、M. Carmen Torralba、M. Rosario Torres
DOI:10.1016/j.tet.2016.04.072
日期:2016.7
A simple and mild protocol towards the regioselective synthesis of 1-aryl/heteroaryl-1-(2-methylimidazo[1,2-a]pyridin-3-yl)methanones has been developed by one-pot condensation of 2-aminopyridine with 1,3-diketones involving the intermediacy of 2-bromo-1,3-diketones formed in situ from 1,3-diketones using N-bromosuccinimide (NBS) in DCM by stirring at room temperature. The structure of the regioisomer