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
tetrabromide mediated oxidative carbon–nitrogen bond formation of 2-aminopyridines or 2-aminopyrimidines with β-keto esters or 1,3-diones, leading to a variety of complex imidazo[1,2-α]pyridines or imidazo[1,2-α]pyrimidines, is reported. The reactions were realized under mild and metal-free conditions.
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
2-Aminopyridines as an α-Bromination Shuttle in a Transition Metal-Free One-Pot Synthesis of Imidazo[1,2-<i>a</i>
]pyridines
作者:Irwan Iskandar Roslan、Kian-Hong Ng、Gaik-Khuan Chuah、Stephan Jaenicke
DOI:10.1002/adsc.201501012
日期:2016.2.4
A wide range of imidazo[1,2‐a]pyridines are accessible from cheap and readily available 2‐aminopyridines and 1,3‐dicarbonyl compounds using a unique CBrCl3/2‐aminopyridine system for bromination at the α‐carbon. 2‐Aminopyridine is not only the substrate but also acts as a bromination shuttle, transferring the bromine atom from CBrCl3 to the α‐carbon of the 1,3‐dicarbonyl. The reaction mechanism involves
使用独特的CBrCl 3 / 2-氨基吡啶体系在α-碳上进行溴化,可以从便宜且容易获得的2-氨基吡啶和1,3-二羰基化合物中获得各种咪唑并[1,2- a ]吡啶。2-氨基吡啶不仅是底物,而且还用作溴化穿梭,将溴原子从CBrCl 3转移到1,3-二羰基的α-碳上。该反应机理涉及一系列可逆步骤,包括具有环状过渡态的加成反应,以形成溴血红素中间体。在这种无过渡金属的单锅合成中,在温和的条件下和较短的反应时间下,分离出的产率高达97%。