A Synthesis of N-(1H-Pyrazol-5-yl)-1,3,4-thiadiazol-2(3H)-imines via Double Cycloaddition Reaction of Nitrile Imines with Erlenmeyer Thioazlactones

Pyrazoles represent an important structural subunit in natural products and drug molecules. Due to their unique pharmacological properties and biological activities, they occupy an important position in heterocyclic chemistry. Many small-molecule drugs contain the pyrazole moiety. Currently, pyrazoles are employed as key constituents of ligands for transition metals, receptors in supramolecular chemistry, liquid crystals and polymers.1 1,3,4-Thiadiazole is a unique template that is associated with several biological activities. 2-Amino-1,3,4-thiadiazole occupy an important place in pharmaceutical chemistry. Some of the best-known drugs based on 2-amino-1,3,4-thiadiazole, are acetazolamide, methazolamide, and megazol.2 During the course of an investigation aimed to the synthesis of pyrazole derivatives, we investigated the reaction between N-phenylbenzohydrazonoyl chloride (1a) and 4-benzylidene-2-(benzylthio)thiazol-5(4H)-one (2a) in the presence of Et3N in MeCN. After work-up, the desired product N-(3,5-diphenyl-1,3,4-thiadiazol-2(3H)-ylidene)-1,3,4-triphenyl-1H-pyrazol-5-amine (3a) was isolated in 98% yield.

کلیدواژه ها:

Pyrazoles ، 2-Amino-1 ، 3 ، 4-thiadiazole ، 1 ، 3-Dipolar cycloaddition ، Nitrile imines