Synthesis and in Vitro Cytotoxic Evaluation of New Derivatives of Pyrido[1,2-a]benzimidazolic Ring System: The Pyrido[1',2':1,2]imidazo[4,5-h]quinazolines.
Elements as Direct Feedstocks for Organic Synthesis: Fe/I<sub>2</sub>/O<sub>2</sub> for Diamination of 2-Cyclohexenones with 2-Aminopyrimidine and 2-Aminopyridines
Elements as feedstocks for organic synthesis, the trio of metallic iron, molecular iodine, and dioxygen, were found to be an excellent tool for oxidative regioselectivediamination of conjugated enones with 2-aminopyrimidine (a guanidine surrogate) and 2-aminopyridines leading to unaromatized coupled products in moderate to good yields.
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.
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%。
Iodine/Copper Iodide-Mediated C–H Functionalization: Synthesis of Imidazo[1,2-<i>a</i>]pyridines and Indoles from <i>N</i>-Aryl Enamines
A practical intramolecular C–H functionalization reaction of N-aryl enamines has been carried out with molecular iodine (I2) as the sole oxidant in the presence of copper iodide (CuI). The efficient and versatile synthetic method described here is compatible with both N-heteroaryl and N-aryl substituted enamines and produces diverse imidazo[1,2-a]pyridine and indole derivatives via I2-mediated oxidative
在碘化铜(CuI)存在下,以分子碘(I 2)为唯一氧化剂,进行了N-芳基烯胺的分子内C–H官能化反应。本文所述的高效且通用的合成方法与N-杂芳基和N-芳基取代的烯胺兼容,并通过I 2生成各种咪唑并[1,2- a ]吡啶和吲哚衍生物介导的氧化性C–N和C–C键的形成。这种无配体的C–H官能化方法也可以与粗制烯胺一起使用,这可以直接从芳胺和酮(或炔烃)直接合成产物,而无需纯化烯胺中间体。
Hypervalent Iodine(III)‐Mediated Counteranion Controlled Intramolecular Annulation of Exocyclic β‐Enaminone to Carbazolone and Imidazo[1,2‐<i>a</i>]pyridine Synthesis
作者:Dhananjay Bhattacherjee、Shankar Ram、Arvind Singh Chauhan、Yamini、Sheetal、Pralay Das
DOI:10.1002/chem.201806299
日期:2019.4.23
A highly efficient and flexible protocol for intramolecular annulation of exocyclic β‐enaminones has been disclosed for the synthesis of carbazolones and imidazo[1,2‐a]pyridines through a counter‐anion‐controlled free‐radical mechanism promoted by hypervalentiodine(III). The cooperative behavior of HTIB and AgSbF6 plays a crucial role in the intramolecular annulation process through C−C and C−N bond
为环外β-烯胺酮的分子内环化一个高效和灵活的协议已经公开了carbazolones和咪唑并[1,2的合成一个]吡啶通过高价碘促进的抗衡阴离子控制自由基机理(III) 。HTIB和AgSbF 6的协同行为在通过CC和CN键形成所需的分子内环化过程中起着至关重要的作用。机械学的见解表明,系统中涉及的两个竞争性反应是由抗衡阴离子的性质决定的,抗衡阴离子的性质决定了最终产物的形成。制备并分离了各种咔唑酮和咪唑并[1,2- a ]吡啶分子,收率良好至极佳。