Nickel catalyzed sustainable synthesis of benzazoles and purines <i>via</i> acceptorless dehydrogenative coupling and borrowing hydrogen approach
作者:Gargi Chakraborty、Rakesh Mondal、Amit Kumar Guin、Nanda D. Paul
DOI:10.1039/d1ob01154e
日期:——
benzoxazole via acceptorless dehydrogenative functionalization of alcohols. Using a bench stable, easy to prepare, and inexpensive Ni(II)-catalyst, [Ni(MeTAA)] (1a), featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)), a wide variety of polysubstituted benzimidazole, purine, benzothiazole, and benzoxazole derivatives were prepared via dehydrogenative coupling of alcohols with
“All-water” chemistry of tandem N-alkylation–reduction–condensation for synthesis of N-arylmethyl-2-substituted benzimidazoles
作者:Damodara N. Kommi、Dinesh Kumar、Rohit Bansal、Rajesh Chebolu、Asit K. Chakraborti
DOI:10.1039/c2gc36377a
日期:——
also exerts a beneficial effect in the condensation of N-monobenzylated o-phenylenediamines with aldehydes. The water-assisted C–N bond formation chemistry led to metal/base-free synthesis of N-monobenzylated o-nitroanilines and N-monobenzylated o-phenylenediamines. The indispensable/advantageous role of water in the various stage of the N-alkylation–reduction–condensation process exemplifies an ‘all-water’
“All-water” one-pot diverse synthesis of 1,2-disubstituted benzimidazoles: hydrogen bond driven ‘synergistic electrophile–nucleophile dual activation’ by water
作者:Damodara N. Kommi、Pradeep S. Jadhavar、Dinesh Kumar、Asit K. Chakraborti
DOI:10.1039/c3gc37004f
日期:——
promoting the subsequent nitro reduction and in the final cyclocondensation steps. The role of water in promoting the cyclocondensation reaction through hydrogen bonds is realized by the differential product yields during the reaction of mono-N-phenyl-o-phenylenediamine with benzaldehyde performed separately in water and D2O. The better hydrogen bond donor and hydrogen bond acceptor abilities of water
One-pot strategy of copper-catalyzed synthesis of 1,2-disubstituted benzimidazoles
作者:Caixia Xie、Xushuang Han、Jian Gong、Danyang Li、Chen Ma
DOI:10.1039/c7ob00945c
日期:——
A simple, one-pot and copper-catalyzed coupling reaction for the construction of 1,2-disubstituted benzimidazole derivatives is described. Low-cost copper salt and weak base K3PO4 were utlized in this reaction. A variety of 1,2-disubstituted benzimidazoles were obtained in moderate to excellent yields.
which starts from N,N′-dialkyl o-phenylenediamines via intramolecular dehydrogenative coupling under the oxidation of DDQ with mild conditions. Through detailed optimization of reaction conditions, only DDQ was found essential without any additives to reach to the highest yield of 99%. In the cases of linear aliphatic substituents, the synthesis of 1-alkyl-2-phenylbenzimidazoles showed high selectivities