The efficient o-benzenedisulfonimide catalysed synthesis of benzothiazoles, benzoxazoles and benzimidazoles

Abstract

o-Benzenedisulfonimide has been used to efficiently catalyse the reaction between 2-aminothiophenol, 2-aminophenol, o-phenylenediamine and various ortho esters (28 examples; average yield 90%) or aldehydes (17 examples; average yield 72%) giving the corresponding benzofused azoles in excellent yields. Reaction conditions were very simple. In addition, other carboxylic acid derivatives have been tested and gave good results. The catalyst was easily recovered and reused.

Facile Synthesis of Benzimidazoles via N-Arylamidoxime Cyclization

“…Benzimidazole compounds have attracted great interest of researchers, and many synthetic methods were developed due to their various biological activities and wide applications in the past several decades. Generally, benzimidazole compounds were most often constructed by condensation of o -phenylenediamines with carboxylic acid derivatives − as well as aldehydes, − ketones, primary aliphatic amines, and alcohols , (Scheme A). Additionally, the synthesis of benzamidines from amidines through metal-catalyzed or oxidative cyclization was also explored (Scheme B). − Recently, benzimidazoles were generated from N -phenylamidoxime esters with the iridium photocatalyst …”

Tungstate sulfuric acid as an efficient catalyst for the synthesis of benzoxazoles and benzothiazoles under solvent-free conditions

“…The products were isolated and characterized by physical and spectroscopic techniques and they were compared with authentic samples [28][29][30][31][32].…”

Benzothiazoles from Condensation of o-Aminothiophenoles with Carboxylic Acids and Their Derivatives: A Review

“…The reaction conditions were very simple. The catalyst was easily recovered and reused (Scheme 40) [150]. A solvent-free method, with sulfonated rice husk ash (RHA) as the solid acid catalyst, was developed for the condensation of ATP with orthoesters in the preparation of BT 46a and 2-methylBT 46b in 92% and 95% yields in 1 min.…”

“…In simple reaction conditions, the condensation of ATP with various acid chlorides in the presence of o-benzenedisulfonimide as the catalyst has been carried out in 2-3.5 h to give the respective 2-substitutedBTs 72 in 42-87% yields (Scheme 52) [150].…”