在室温下开发了一种简单的醚与氰胺的可见光光氧化还原催化的自由基级联环化反应。该策略涉及通过氧烷基自由基与N-氰基的分子间加成反应,随后通过C-2芳基环原位产生的亚氨基自由基的自由基环化,依次进行惰性C sp3- H / C sp2- H官能化。该方法可以有效合成四环苯并[4,5]咪唑并[1,2- c ]喹唑啉。重要的是,这是氰酰胺分子间-分子间自由基级联环化反应的第一个例子。
Synthesis of some benzimidazole derivatives via condensation reaction of o-phenylenediamine derivatives with aromatic aldehydes or orthoesters under solvent-free conditions over nano-Ni(II)/Y zeolite as a heterogeneous catalyst is reported. Some advantages of this green method are easy purification, environmentally friendly conditions, low catalyst loadings, and nontoxic nature.
Novel molecular iodine catalyzed cyclization reactions of 2-amino anilines with aryl alkyl ketones under oxidant and metal-free conditions are described. The reaction likely involves sequential C–N bond formation followed by C(CO)–C(alkyl) bondcleavage. Various 2-substituted benzimidazoles are obtained in moderate to good yields in a single step from readily available acetophenones, propiophenones
The catalytic dehydrogenation and tandem transformation of aromatic alcohols, including oxidative coupling of alcohols and amines, were achieved successfully using a catalytic amount of organosilicon-supported titania (TiO2@PMHSIPN), which enables the efficient synthesis of aromatic aldehydes, imines, and benzimidazoles in good to excellent yields.
NaHSO3 was more than 11 equivalents, the 2-substituted benzimidazole could be highly selectively formed as the sole product. NaHSO3 was firstly reacted with aldehyde to form the aldehyde sodium bisulfite, which reacted with o-phenylenediamine to form the 2-substituted benzimidazole and inhibited the formation of 1,2-disubstituted benzimidazole. This protocol solved the poor selectivity problem appearing
Fe3O4@SiO2/collagen: An efficient magnetic nanocatalyst for the synthesis of benzimidazole and benzothiazole derivatives
作者:Hossein Ghafuri、Elahe Esmaili、Majid Talebi
DOI:10.1016/j.crci.2016.05.003
日期:2016.8
Résumé In this project, Fe3O4@SiO2 was synthesized and combined with collagen for the preparation of Fe3O4@SiO2/collagen. It was characterized by FT-IR, 1H NMR, VSM, XRD, EDX, SEM and TEM. This nanocatalyst has some interesting advantages such as facile synthetic procedure, high catalytic activity, easy separation and acceptable reusability. It was applied as an efficient nanocatalyst in the synthesis of benzimidazole and benzothiazole derivatives. This method offers several advantages including high yields, short reaction times, easy workup process and environmentally benign reaction conditions.