Diphenhydramine Hydrochloride-CuCl as a New Catalyst for the Synthesis of Tetrahydrocinnolin-5(1H)-ones

Efficient synthesis of novel thiadiazolo[2,3-b]quinazolin-6-ones catalyzed by diphenhydramine hydrochloride-CoCl⋅6H2O deep eutectic solvent

In this research, a new Lewis acid-based deep eutectic solvent (LA-DES) was synthesized using diphenhydramine hydrochloride and CoCl2·6H2O, (2[HDPH]:CoCl42-), and identified by FT-IR and 1HNMR techniques. The physicochemical properties of this LA-DES, such as thermal behavior, thermal stability, and solubility in common solvents were also investigated. The catalytic ability of 2[HDPH]:CoCl42- was ascertained in the efficient synthesis of a novel array of thiadiazolo[2,3-b]quinazolin-6-one scaffolds via a one-pot three-component reaction of dimedone/1,3-cyclohexanedione, aldehydes, and 5-aryl-1,3,4-thiadiazol-2-amines/3-(5-amino-1,3,4-thiadiazol-2-yl)-2H-chromen-2-one under solvent-free conditions. This catalyst was also successfully utilized for the synthesis of mono- and bis-thiadiazolo[2,3-b]quinazolin-6-ones from dialdehydes or bis-1,3,4-thiadiazol-2-amine. The simplicity of enforcement, short reaction time, avoidance of toxic organic solvents, scalability of the synthesis procedure, excellent atom economy, high reaction mass efficiency, and low E-factor are other outstanding advantages of this newly developed method. Furthermore, due to the convenient recovery and reuse of LA-DES, this protocol is economically justified and environmentally friendly.

Triazine diphosphonium tetrachloroferrate ionic liquid immobilized on functionalized halloysite nanotubes as an efficient and reusable catalyst for the synthesis of mono-, bis- and tris-benzothiazoles

Aminopropyl-1,3,5-triazine-2,4-diphosphonium tetrachloroferrate immobilized on halloysite nanotubes [(APTDP)(FeCl4)2@HNT] was prepared and fully characterized using different techniques such as FT-IR, thermogravimetric analysis (TGA), SEM/EDX, elemental mapping, TEM, ICP-OES, and elemental analysis (EA). This nanocatalyst was found to be highly effective for synthesis of various benzothiazole derivatives in excellent yields under solvent-free conditions. Furthermore, bis- and tris-benzothiazoles were smoothly synthesized from dinitrile and trinitrile in the presence of this catalytic system. High yields and purity, easy work up procedure, high catalytic activity (high TON and TOF) and easy recovery and reusability of the catalyst make this method a useful and important addition to the present methodologies for preparation of these vital heterocyclic compounds.