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 boron trifluoride 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