582-60-5Relevant academic research and scientific papers
One-Pot Transformation of Lignin and Lignin Model Compounds into Benzimidazoles
Guo, Tao,He, Jianghua,Liu, Tianwei,Zhang, Yuetao
supporting information, (2022/02/07)
It is a challenging task to simultaneously achieve selective depolymerization and valorization of lignin due to their complex structure and relatively stable bonds. We herein report an efficient depolymerization strategy that employs 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as oxidant/catalyst to selectively convert different oxidized lignin models to a wide variety of 2-phenylbenzimidazole-based compounds in up to 94 % yields, by reacting with o-phenylenediamines with varied substituents. This method could take full advantage of both Cβ and/or Cγ atom in lignin structure to furnish the desirable products instead of forming byproducts, thus exhibiting high atom economy. Furthermore, this strategy can effectively transform both the oxidized hardwood (birch) and softwood (pine) lignin into the corresponding degradation products in up to 45 wt% and 30 wt%, respectively. Through a “one-pot” process, we have successfully realized the oxidation/depolymerization/valorization of natural birch lignin at the same time and produced the benzimidazole derivatives in up to 67 wt% total yields.
Preparation method of 5, 6-dimethylbenzimidazole
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Paragraph 0007, (2021/06/06)
The invention discloses a preparation method of 5, 6-dimethyl benzimidazole. The preparation method comprises the following four steps: preparation of N-(3, 4-dimethyl phenyl) formamide, preparation of N-(4, 5-dimethyl-2-nitrophenyl) formamide, preparation of N-(2-amino-4, 5-dimethyl phenyl) formamide, and preparation of 5, 6-dimethyl benzimidazole. The preparation method has the following beneficial effects: 1, acetylation and deacetylation used in the prior art are avoided, which is in favor of environmental protection; 2, the synthesis steps of the process are shortened, the original five-step reaction is shortened to the present four-step reaction, and the yield is improved; and 3, the purity of the intermediate is high, separation is not needed, the operation is simple, the defects and deficiencies of the preparation method reported in the literature are overcome, and the method has novelty, greater positive progress effect and practical application value.
A substituent- And temperature-controllable NHC-derived zwitterionic catalyst enables CO2upgrading for high-efficiency construction of formamides and benzimidazoles
Li, Hu,Li, Zhengyi,Wu, Hongguo,Yang, Song,Yu, Zhaozhuo,Zhang, Lilong,Zhu, Kaixun
supporting information, p. 5759 - 5765 (2021/08/23)
Chemocatalytic upgrading of the greenhouse gas CO2 to valuable chemicals and biofuels has attracted broad attention in recent years. Among the reported approaches, N-formylation of CO2 with an amine is of great significance due to its versatility in the construction of N-containing linear and cyclic skeletons. Herein, a stable N-heterocyclic carbene-carboxyl adduct (NHC-CO2) was facilely prepared and could be used as a recyclable zwitterionic catalyst for efficient CO2 reductive upgrading via either N-formylation or further coupling with cyclization under mild conditions (25 °C, 1 atm CO2) using hydrosilane as a hydrogen source. More than 30 different alkyl and aromatic amines could be transformed into the corresponding formamides or benzimidazoles with remarkable yields (74%-98%). The electronic effect of the introduced substituent on NHC-CO2 was found to evidently affect the thermostability and nucleophilicity of the zwitterionic catalyst, which is directly correlated with its catalytic activity. Moreover, NHC-CO2 could supply CO2 by in situ decarboxylation at a specific temperature that is dependent on the introduced substituent type. Experimental and computational studies showed that the carboxyl species on NHC-CO2 was not only a nucleophilic center, but also a C1 source which rapidly captures or substitutes ambient CO2 during hydrosilylation. In addition, a simple and green conceptual process was designed for the product purification and catalyst recycling, with a good feasibility for small-scale production.
Reductive cyclization of o-phenylenediamine with CO2 and BH3NH3 to synthesize 1H-benzoimidazole derivatives
Han, Limin,Hong, Hailong,Li, Xiao,Yang, Yue,Zhang, Junhua,Zhu, Ning
supporting information, (2021/09/28)
A simple and green protocol was developed for the reductive cyclization of o-phenylenediamine with CO2 and BH3NH3 to yield 1H-benzimidazole. The desired 1H-benzimidazole derivatives were produced under mild conditions. Mechanism investigation indicated that the coordination of o-phenylenediamine with the boron atom of BH3NH3 promoted the transfer of the formyl group to form a stable intermediate, which facilitated the intramolecular nucleophilic addition-elimination for the formation of target product. In this process, BH3NH3 served multifunctional roles, acting as a reducing agent and a formylation catalyst.
Highly efficient one pot synthesis of benzimidazoles from 2-nitroaniline and PhSiH3 as reducing agent catalyzed by Pd/C as a heterogeneous catalyst
Phatake, Vishal V.,Bhanage, Bhalchandra M.
, (2021/03/15)
This work reports an efficient route for the synthesis of benzimidazole from o-nitroaniline in the presence of carbon dioxide atmosphere, PhSiH3 as a reducing agent catalyzed by Pd/C as a catalyst. Benzimidazoles have become the focus of organic chemists, as benzimidazole is an important intermediate in medicinal chemistry. We have developed more efficient route for the synthesis benzimidazole and various substituted benzimidazoles have been synthesized in good to excellent yield. The TBD (1,5,7-Triazabicyclo [4.4.0] dec-5-ene) is selected as a base as it promotes the CO2 insertion. Benzimidazoles were synthesized through reduction of nitro group followed by cyclization of amine using CO2 as a carbon source. Moreover, the Pd/C catalyst can be recycled up to five recycle run without significant changes in the yield of the product.
Accelerated microdroplet synthesis of benzimidazoles by nucleophilic addition to protonated carboxylic acids
Basuri, Pallab,Gonzalez, L. Edwin,Morato, Nicolás M.,Pradeep, Thalappil,Cooks, R. Graham
, p. 12686 - 12694 (2020/12/29)
We report a metal-free novel route for the accelerated synthesis of benzimidazole and its derivatives in the ambient atmosphere. The synthetic procedure involves 1,2-aromatic diamines and alkyl or aryl carboxylic acids reacting in electrostatically charged microdroplets generated using a nano-electrospray (nESI) ion source. The reactions are accelerated by orders of magnitude in comparison to the bulk. No other acid, base or catalyst is used. Online analysis of the microdroplet accelerated reaction products is performed by mass spectrometry. We provide evidence for an acid catalyzed reaction mechanism based on identification of the intermediate arylamides. Their dehydration to give benzimidazoles occurs in a subsequent thermally enhanced step. It is suggested that the extraordinary acidity at the droplet surface allows the carboxylic acid to function as a C-centered electrophile. Comparisons of this methodology with data from thin film and bulk synthesis lead to the proposal of three key steps in the reaction: (i) formation of an unusual reagent (protonated carboxylic acid) because of the extraordinary conditions at the droplet interface, (ii) accelerated bimolecular reaction because of limited solvation at the interface and (iii) thermally assisted elimination of water. Eleven examples are shown as evidence of the scope of this chemistry. The accelerated synthesis has been scaled-up to establish the substituent-dependence and to isolate products for NMR characterization.
Carbonylative Acetylation of Heterocycles
Zhang, Youcan,Yin, Zhiping,Wu, Xiao-Feng
supporting information, p. 213 - 216 (2020/01/22)
Herein, a new procedure for the carbonylative acetylation of heterocycles has been developed. In this process, organic peroxide acts as the methyl source. Various heterocycles were transformed into the corresponding methyl heterocyclic ketones in moderate to good yields.
K2S as Sulfur Source and DMSO as Carbon Source for the Synthesis of 2-Unsubstituted Benzothiazoles
Deng, Guobo,Kuang, Daizhi,Liang, Yun,Yang, Yuan,Yu, Jiangxi,Zhang, Fuxing,Zhu, Xiaoming
supporting information, p. 3789 - 3793 (2020/06/04)
We describe a three-component reaction of o-iodoanilines with K2S and DMSO that provides 2-unsubstituted benzothiazoles in moderate to good isolated yields with good functional group tolerance. Electron-rich aromatic amines and o-phenylenediamines instead of o-iodoanilines provided 2-unsubstituted benzothiazoles and 2-unsubstituted benzimidazoles with and without K2S under similar conditions. Notably, DMSO plays three vital roles: carbon source, solvent, and oxidant.
Synthesis method of ammonium acetate mediated benzimidazole compound
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Paragraph 0060-0062, (2020/11/23)
The invention discloses a synthesis method of a benzimidazole compound mediated by ammonium acetate. The synthesis method comprises the following steps: adding an o-phenylenediamine compound, dimethylsulfoxide, an additive 1 and an additive 2 into a reaction tube, carrying out a stirring reaction at 130-150 DEG C, cooling the reaction product to room temperature after the reaction is finished, and carrying out separation and purification on the product to obtain the benzimidazole compound. The invention develops a method for synthesizing a benzimidazole compound under the mediation of ammonium acetate by taking DMSO as a carbon source and an oxidant and an o-phenylenediamine compound as a substrate under the condition of no metal catalyst. The synthesis method does not need a metal catalyst, and the required carbon source and oxidant have the characteristics of low toxicity, low price, easiness in obtaining, stable performance and the like. The method has the advantages of easiness inoperation, few steps, mild reaction conditions, better functional group tolerance and the like, and provides a new valuable way for synthesizing benzimidazole compounds.
Facile access to: N-formyl imide as an N-formylating agent for the direct synthesis of N-formamides, benzimidazoles and quinazolinones
Huang, Hsin-Yi,Liang, Chien-Fu,Lin, Xiu-Yi,Yen, Shih-Yao
supporting information, p. 5726 - 5733 (2020/08/21)
N-Formamide synthesis using N-formyl imide with primary and secondary amines with catalytic amounts of p-toluenesulfonic acid monohydrate (TsOH·H2O) is described. This reaction is performed in water without the use of surfactants. Moreover, N-formyl imide is efficiently synthesized using acylamidines with TsOH·H2O in water. In addition, N-formyl imide was successfully used as a carbonyl source in the synthesis of benzimidazole and quinazolinone derivatives. Notable features of N-formylation of amines by using N-formyl imide include operational simplicity, oxidant- A nd metal-free conditions, structurally diverse products, and easy applicability to gram-scale operation.
