Phosphine-Free Palladium-Catalyzed Direct Arylation of Imidazo[1,2-a]pyridines with Aryl Bromides at Low Catalyst Loading
作者:Hai Yan Fu、Lu Chen、Henri Doucet
DOI:10.1021/jo300528b
日期:2012.5.4
Ligand-free Pd(OAc)2 was found to catalyze very efficiently the directarylation of imidazo[1,2-a]pyridines at C3 under very low catalyst concentration. The reaction can be performed employing as little as 0.1–0.01 mol % catalyst with electron-deficient and some electron-excessive aryl bromides.
catalytic amount of Fe(TPP)Cl and Zn dust. The reaction precludes the traditional, more favored click reaction between an organic azide and alkynes, and instead proceeds by an unprecedented metalloradicalactivation. The method is anticipated to advance access to the construction of important basic nitrogen heterocycles, which will in turn enable discoveries of new drug candidates.
Direct C-3 arylation of imidazo[1,2-a]pyridines with aryl tosylates and mesylates has been accomplished by employing palladium(II) acetate associated with SPhos (2-dicyclohexylphosphino-2′,6′-dimethoxybiphenyl) or L1 (2-(2-(diisopropylphosphino)phenyl)-1-methyl-1H-indole). This catalyst system can be applied to a wide range of aryl sulfonates and shows excellent C-3 regioselectivity of imidazo[1,2-a]pyridine
咪唑并直接C-3的芳基化[1,2一]吡啶与芳基甲苯磺酸酯和甲磺酸酯已通过采用钯完成(II)与SPhos(2-二环己基膦基-2',6'-二甲氧基联苯)或相关联的醋酸L1(2 -(2-(二异丙基膦基)苯基)-1-甲基-1 H-吲哚)。该催化剂体系可用于各种芳基磺酸盐,并显示出优异的咪唑并[1,2- a ]吡啶的C-3区域选择性。这些结果代表了使用甲苯磺酸酯和甲磺酸酯官能化的芳烃作为该区域选择性直接芳基化的亲电子伙伴的第一个例子。
On water direct arylation of imidazo[1,2- a ]pyridines with aryl halides
作者:Saradhi Kalari、Dattatraya A. Babar、Uttam B. Karale、Vitthal B. Makane、Haridas B. Rode