Synthesis Of Benzothiazoles Research Articles

Ionic Liquid-Catalyzed C–S Bond Construction using CO2 as a C1 Building Block under Mild Conditions: A Metal-Free Route to Synthesis of Benzothiazoles

The construction of the C–S bond using CO2 as a C1 feedstock can be considered as a green route for the synthesis of S-containing compounds and is of great significance. Herein, we report the acetate-based ionic liquids (ILs)-catalyzed synthesis of benzothiazoles via cyclization of 2-aminothiophenols with CO2 and hydrosilane under mild conditions (e.g., 60 °C, 0.5 MPa). It was found that the IL (e.g., 1-butyl-3-methylimidazolium acetate, [Bmim][OAc]) served as a multifunctional catalyst with activating CO2 and hydrosilane to form a formoxysilane intermediate, as well as simultaneously activating 2-aminothiophenols through a hydrogen bond, finally resulting in the production of benzothiazoles. [Bmim][OAc] showed the best performance, and a series of benzothiazoles were obtained in high yields. To the best of our knowledge, this is the first protocol for the synthesis of benzothiazoles using CO2 as a C1 building block under metal-free and mild conditions.

Efficient, microwave-mediated synthesis of benzothiazole- and benzimidazole-based heterocycles

1-(Benzothiazol-2-yl)-3-(N,N-dimethylamino)-2-(phenylsulfonyl)prop-2-en-1-one (3) and 1-(1-methylbenzimidazol-2-yl)-3-(N,N-dimethylamino)-2-(phenylsulfonyl)prop-2-en-1-one (4) were obtained from the reaction of 1-(benzothiazothiazol-2-yl)-2-phenylsulfonyl-1-ethanone (1) and 1-(1-methyl-1H-benzimidazol-2-yl)-2-(phenylsulfonyl)-1-ethanone (2) with N,N-dimethylformamide dimethyl acetal, respectively. The enaminosulfones 3 and 4 were used as versatile building blocks for the synthesis of novel pyrazolo[1,5-a]pyrimidine and [1,2,4]-triazolo[1,5-a]pyramidine derivatives via their reactions with the appropriate aminopyrazoles and aminotriazole under both microwave and thermal reaction conditions. They have been also utilized as reactive synthons for the construction of novel pyrimido[1,2-a]benzimidazole, pyrido[1,2-a]benzimidazole, pyrimidine, isoxazole and pyrazole heterocycles pendent to benzothiazole and benzimidazole ring systems.

Synthesis of Benzothiazoles by the Reaction of Disulfide and Aromatic Carboxylic Acid Promoted by PCL3 and DBU

GRAPHICAL ABSTRACT

ChemInform Abstract: A Metal‐Free and Recyclable Synthesis of Benzothiazoles Using Thiourea as a Sulfur Surrogate.

AbstractTreatment of substrates (I) with thiourea and TFA gives benzothiazoles (IV) and TFA salts (V).

Acceptorless dehydrogenative synthesis of benzothiazoles and benzimidazoles from alcohols or aldehydes by heterogeneous Pt catalysts under neutral conditions

Pt/Al2O3 and Pt/TiO2 were effective catalysts for the synthesis of 2-substituted benzothiazoles and benzimidazoles from 2-aminothiophenol and 1,2-phenylenediamine with alcohols or aldehydes under acceptor-free and additive-free conditions.

ChemInform Abstract: Yttrium‐Catalyzed Heterocyclic Formation via Aerobic Oxygenation: A Green Approach to Benzothiazoles.

Abstract The YCl 3 -catalyzed aerobic oxidative cyclization reaction for the synthesis of benzothiazoles has been developed. This method provides a practical, effective and green synthetic approach to benzothiazoles which are important units in many biologically active compounds.

ChemInform Abstract: Hydrosilane‐Promoted Cyclization of 2‐Aminothiophenols by CO2 to Benzothiazoles.

AbstractThe method is an environmentally benign approach for the synthesis of benzothiazoles and achieves the C‐S chemical bond construction using CO2 as C‐1 building block.

ChemInform Abstract: A Ball‐Milling Strategy for the Synthesis of Benzothiazole, Benzimidazole and Benzoxazole Derivatives under Solvent‐Free Conditions.

AbstractThe synthesis of benzothiazoles, benzimidazoles, and benzoxazoles is performed at ambient temperature under solvent‐free conditions in a ball mill in relatively short reaction times.

ChemInform Abstract: A Simple Approach to Benzothiazoles from 2‐Chloronitrobenzene, Elemental Sulfur, and Aliphatic Amine under Solvent‐Free and Catalyst‐Free Conditions.

Abstract A novel solvent-free and catalyst-free synthesis of benzothiazoles from 2-chloronitrobenzene, elemental sulfur, and aliphatic amine has been developed. The reaction tolerated a wide range of functionalities, and various benzothiazoles were synthesized in moderate to good yields in the absence of external oxidant or reductant.

A metal-free and recyclable synthesis of benzothiazoles using thiourea as a sulfur surrogate

Using odorless thiourea as the S source, benzothiazoles and asymmetric disulfides could be obtained from thioformanilides through the tandem cyclization/nucleophilic addition/hydrolysis/nucleophilic substitution reaction. Furthermore, the obtained asymmetric disulfides could readily transfer to benzothiazoles after nitro-reduction and amide formation reaction. This metal-free and recyclable synthetic methodology offered a time-efficient, less expensive, and environmentally friendly alternative to multifunctional benzothiazoles.

ChemInform Abstract: Syntheses of 2‐Aryl Benzothiazoles via Photocatalyzed Oxidative Condensation of Amines with 2‐Aminothiophenol in the Presence of BODIPY Derivatives.

Abstract A simple, convenient, and efficient new method for synthesis of 2-aryl benzothiazoles under mild conditions with nonmetal catalyst has been developed. Boron–dipyrromethene (BODIPY) dyes were used as photocatalysts for aerobic oxidative reactions of amine with 2-aminothiophenol. The approach will be very useful for the synthesis of benzothiazole derivatives and the development of photocatalytic reactions.

ChemInform Abstract: Quaternary Ammonium Salt as Alkylation Agent in Three‐Component Reactions for the Synthesis of Benzothiazoles in Water.

AbstractThe synthesis of benzothiazoles is achieved from haloanilines, sulfur powder, and quaternary ammonium salts which act as alkylation reagents as well as phase transfer catalysts in aqueous medium.

Piperazinylpyrimidine modified MCM-41 for the ecofriendly synthesis of benzothiazoles by the simple cleavage of disulfide in the presence of molecular O2

Synthesis of benzothiazoles by metal free cleavage of disulfide bond.

Formation of a nanorod shaped ionogel and its high catalytic activity for one-pot synthesis of benzothiazoles

Synthesis of an ionogel using 1,3,5-trimethylpyrazoliumchloride and its application in high catalytic synthesis of benzothiazole derivatives.

Efficient sodium bisulfite-catalyzed synthesis of benzothiazoles and their potential as ureases inhibitors

In this work we report the successful use of sodium bisulfite as catalyst for the synthesis of 19 benzothiazoles (BZTs) under microwave irradiation with yields from 80% to 100%.

Metal-Free Synthesis of Benzothiazoles from Disulfides of 2-Aminobenzenethiol and Carboxylic Acid via PCl3-Promoted Tandem Reaction

Metal-Free Synthesis of Benzothiazoles from Disulfides of 2-Aminobenzenethiol and Carboxylic Acid via PCl3-Promoted Tandem Reaction

Samarium(III) triflate: a new catalyst for facile synthesis of benzothiazoles and benzoxazoles from carboxylic acids in aqueous media

A facile synthetic method for benzothiazoles and benzoxazoles comprising the reaction of corresponding 2-aminothiophenol and 2-aminophenol with various substituted aromatic carboxylic acids using Samarium(III) triflate as a catalyst has been described. The advantages of the method are short reaction times and aqueous reaction media and easy work-up. The catalysts can be recovered for the subsequent reactions and reused without any appreciable loss of efficiency.

Yttrium-catalyzed heterocyclic formation via aerobic oxygenation: A green approach to benzothiazoles

Abstract The YCl 3 -catalyzed aerobic oxidative cyclization reaction for the synthesis of benzothiazoles has been developed. This method provides a practical, effective and green synthetic approach to benzothiazoles which are important units in many biologically active compounds.

Lithium bromide catalyzed efficient and convenient synthesis of 2-arylbenzothiazole derivatives

A new and efficient protocol was developed for synthesis of benzothiazoles using lithium bromide as catalyst under environmentally friendly conditions. The developed synthetic protocol represents a novel and very simple route for preparation of 2-substituted benzothiazole derivatives. In addition, an ultrasound irradiation technique is successfully implemented for carrying out the reactions in shorter reaction times.

Syntheses of 2-Aryl Benzothiazoles via Photocatalyzed Oxidative Condensation of Amines with 2-Aminothiophenol in the Presence of BODIPY Derivatives

A simple, convenient, and efficient new method for synthesis of 2-aryl benzothiazoles under mild conditions with nonmetal catalyst has been developed. Boron–dipyrromethene (BODIPY) dyes were used as photocatalysts for aerobic oxidative reactions of amine with 2-aminothiophenol. The approach will be very useful for the synthesis of benzothiazole derivatives and the development of photocatalytic reactions.