A General Approach to Substituted Benzimidazoles and Benzoxazoles
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Heterogeneous Palladium‐Catalyzed Hydrogen‐Transfer with Primary Amines
作者:Marianna Pizzetti、Elisa De Luca、Elena Petricci、Andrea Porcheddu、Maurizio Taddei
DOI:10.1002/adsc.201200253
日期:2012.9.17
employed. Primaryamines are the most suitable reagents for the atom economy of the overall process that resulted to be general as several different substitutedbenzimidazoles were obtained in good yield. Benzoxazoles can be also prepared starting from primaryamines and o‐aminophenol. The reaction is also highly selective as no (poly)‐alkylated phenylenediamines or cross‐contaminated benzimidazoles are
Silver-loaded TiO2 (Ag–TiO2) and acidic clay (K10 montmorillonite) composite photocatalyst has been successfully applied for the light-induced conversion of o-phenylenediamine (OPD) and its derivatives to substituted benzimidazoles with various alcohols in acetonitrile using UV-A and solar light. The influence of the various photocatalysts, solvents, and substituents on the yield and selectivity of the products has been investigated. The mechanism of photocatalysis is proposed. Loading silver on TiO2 enhances product yield and selectivity both in UV and solar light. In the presence of primary alcohols, 2-aminothiophenol forms only disulfide and hence Ag–TiO2/clay can be used as a green catalyst for the synthesis of disulfides.
An easy one-step photocatalytic synthesis of 1-aryl-2-alkylbenzimidazoles by platinum loaded TiO2 nanoparticles under UV and solar light
作者:K. Selvam、M. Swaminathan
DOI:10.1016/j.tetlet.2011.04.090
日期:2011.6
One-potsynthesis of disubstituted benzimidazoles from N-substituted 2-nitroanilines or 1,2-diamines with 3–12 nm-sized platinum particles loaded on the TiO2 using solar and UV-A light is described. 1-Aryl-2-alkylbenzimidazoles from 2-nitrodiphenylamines are formed by combined redox photocatalyticreaction, condensation and catalytic dehydrogenation on Pt-TiO2. In case of diamines, this reaction is
Oxone-mediated annulation of 2-aminobenzamides and 1,2-diaminobenzenes with<i>sec</i>-amines<i>via</i>imine-<i>N</i>-oxides: new syntheses of 2,3-dihydroquinazolin-4(1<i>H</i>)-ones and 1<i>H</i>-benzimidazoles
An efficient and mild method for the preparation of 2,3-dihydroquinazolin-4(1H)-ones and 1H-benzimidazoles by the oxone-mediated reaction of sec-amines via imine-N-oxides with 2-amino-N-substituted benzamides and 1,2-diaminobenzenes respectively in THF–water (2 : 1) at ambient temperature is described.
Magnetically separable MnFe2O4 nano-material: an efficient and reusable heterogeneous catalyst for the synthesis of 2-substituted benzimidazoles and the extended synthesis of quinoxalines at room temperature under aerobic conditions
作者:Goutam Brahmachari、Sujay Laskar、Puspendu Barik
DOI:10.1039/c3ra41457d
日期:——
A simple and efficient protocol has been developed for the synthesis of biologically relevant 2-substituted benzimidazoles and quinoxalines using magnetically separable manganese ferrite (MnFe2O4) nanopowder for the first time as a reusableheterogeneouscatalyst at room temperature under aerobic conditions. MnFe2O4 nanoparticles were prepared by a simple sol–gel method using starch as a bio-polymeric
已经开发了一种简单有效的方案,首次使用可磁分离的锰铁氧体(MnFe 2 O 4)纳米粉作为可重复使用的非均相催化剂,在室温下好氧条件下合成生物学上相关的2-取代的苯并咪唑和喹喔啉。MnFe 2 O 4纳米粒子是通过简单的溶胶-凝胶法以淀粉为生物聚合物基质制备的,并通过XRD,TEM,EDAX和VSM分析进行了表征。