- Rhodium catalyzed 2-alkyl-benzimidazoles synthesis from benzene-1,2-diamines and tertiary alkylamines as alkylating agents
-
Substituted 2-alkyl-benzimidazoles were synthesized from benzene-1,2-diamine and tertiary amines as alkylating agent under polystyrene supported rhodium (Rh@PS) nanoparticles (NPs) catalyzed conditions. The heterogeneous rhodium catalyst was applied first time for the synthesis of 2-alkyl-benzimidazoles. The reaction followed through oxidation of alkylamines, transamination, and oxidative cyclisation with benzene-1,2-diamines for the corresponding products synthesis with good yields. The process is applicable for vast substrate scope, several functional groups are tolerable, and the Rh@PS catalyst is recyclable up to four cycles without significant loss in catalytic activity.
- Yamini,Sharma, Saurabh,Das, Pralay
-
-
- Iridium-catalyzed C-H borylation of heteroarenes: Scope, regioselectivity, application to late-stage functionalization, and mechanism
-
A study on the iridium-catalyzed C-H borylation of heteroarenes is reported. Several heteroarenes containing multiple heteroatoms were found to be amenable to C-H borylation catalyzed by the combination of an iridium(I) precursor and tetramethylphenanthroline. The investigations of the scope of the reaction led to the development of powerful rules for predicting the regioselectivity of borylation, foremost of which is that borylation occurs distal to nitrogen atoms. One-pot functionalizations are reported of the heteroaryl boronate esters formed in situ, demonstrating the usefulness of the reported methodology for the synthesis of complex heteroaryl structures. Application of this methodology to the synthesis and late-stage functionalization of biologically active compounds is also demonstrated. Mechanistic studies show that basic heteroarenes can bind to the catalyst and alter the resting state from the olefin-bound complex observed during arene borylation to a species containing a bound heteroarene, leading to catalyst deactivation. Studies on the origins of the observed regioselectivity show that borylation occurs distal to N-H bonds due to rapid N-H borylation, creating an unfavorable steric environment for borylation adjacent to these bonds. Computational studies and mechanistic studies show that the lack of observable borylation of C-H bonds adjacent to basic nitrogen is not the result of coordination to a bulky Lewis acid prior to C-H activation, but the combination of a higher-energy pathway for the borylation of these bonds relative to other C-H bonds and the instability of the products formed from borylation adjacent to basic nitrogen.
- Larsen, Matthew A.,Hartwig, John F.
-
supporting information
p. 4287 - 4299
(2014/04/03)
-
- Novel strategy for synthesis of substituted benzimidazo[1,2-a]quinolines
-
An efficient method for the synthesis of benzimidazo[1,2-a]quinolines under transition-metal-free conditions has been developed through a cascade reaction involving sequential aromatic nucleophilic substitution and intramolecular Knoevenagel condensation reactions. This method is applicable for the synthesis of a wide range of benzimidazo[1,2-a]quinoline derivatives from readily available 2-fluoroarylaldehyde and benzimidazole substrates.
- Kato, Jun-Ya,Ito, Yutaro,Ijuin, Ryosuke,Aoyama, Hiroshi,Yokomatsu, Tsutomu
-
supporting information
p. 3794 - 3797
(2013/08/23)
-
- Indium-mediated one-pot benzimidazole synthesis from 2-nitroanilines or 1,2-dinitroarenes with orthoesters
-
One-pot reduction-triggered heterocyclizations from 2-nitroanilines or 1,2-dinitroarenes to benzimidazoles were investigated in this study. In the presence of indium/AcOH in ethyl acetate at reflux, reaction of 2-nitroanilines or 1,2-dinitroarenes with R-C(OMe)3 (R=Me, Ph) produced excellent yields of the corresponding benzimidazoles within 30 min to 6 h depending on the substituents of the starting materials. Indium-mediated heterocyclization of 2-nitroanilines to benzimidazole was faster and had better yields than 1,2-dinitroarenes to benzimidazole under similar reaction conditions.
- Kim, Jaeho,Kim, Jihye,Lee, Hyunseung,Lee, Byung Min,Kim, Byeong Hyo
-
experimental part
p. 8027 - 8033
(2011/11/06)
-
- Expeditious and efficient synthesis of benzoxazoles, benzothiazoles, benzimidazoles catalyzed by Ga(OTf)3 under solvent-free conditions
-
A new and efficient method for the synthesis of benzoxazoles, benzothiazoles, benzimidazoles from reactions of o-substituted aminoaromatics with orthoesters in the presence of catalytic amounts of Ga(OTf)3 under solvent-free conditions is presented. The remarkable features of this new protocol are high conversion, very short reaction times, cleaner reaction profiles under solvent-free conditions, straight forward procedure, and use of relatively non-toxic catalysts.
- Liu, Juyan,Liu, Qian,Xu, Wei,Wang, Weilu
-
experimental part
p. 1739 - 1744
(2012/02/14)
-
- SMALL MOLECULE INHIBITORS OF PLASMODIUM FALCIPARUM DIHYDROOROTATE DEHYDROGENASE
-
Inhibitors of dihydroorotate dehydrogenase (DHODH) for the Plasmodium enzyme have been identified and characterized. The inhibitors have high specificity, submicromolar efficacy against cultured parasite strains, exhibit drug-like properties, and are not overtly cytotoxic.
- -
-
Page/Page column 30
(2010/01/29)
-
- A mild, efficient and one-pot synthesis of 2-substituted benzimidazoles by ZrOCl2. 8H2O catalyzed ring closure reaction
-
A mild, efficient and one-pot synthesis of an array of 2-substituted benzimidazoles from an appropriate o-phenylenediamine and orthoesters such as orthoformate, orthoacetate and orthovalerate using ZrOCl2-8H 2O, at room temperature and under microwave irradiation is described. Ecofriendly, solvent-free methodology has been employed under microwave condition. Compared with the conventional method, microwave irradiation method has the advantages of excellent yields (81-93%) and shorter reaction time (5-10 min).
- Sanjeeva Reddy,Nagaraj
-
experimental part
p. 1154 - 1159
(2009/04/11)
-
- A highly effective sulfamic acid/methanol catalytic system for the synthesis of benzimidazole derivatives at room temperature
-
Sulfamic acid/methanol was found to be an efficient catalytic system for the synthesis of benzimidazole compounds through the condensation of o-phenylenediamine with orthoester in high yields at room temperature.
- Zhang, Zhan-Hui,Li, Tong-Shuang,Li, Jian-Jiong
-
-
- Synthesis of 2-substituted benzimidazoles by iodine-mediated condensation of orthoesters with 1,2-phenylenediamines
-
(Chemical Equation Presented) Iodine was found to be an efficient catalyst for the synthesis of 2-substituted benzimidazoles by the condensation of orthoesters and 1,2-phenylenediamines in good to excellent yields under mild reaction conditions.
- Zhang, Zhan-Hui,Li, Jian-Jiong,Gao, Yuan-Zhe,Liu, Yu-Heng
-
p. 1509 - 1512
(2008/09/18)
-