title: Photocatalysis by 3,6-disubstituted-s-tetrazine: visible-light driven metal-free green synthesis of 2-substituted benzimidazole and benzothiazole.
abstract: s-Tetrazine based molecules were prepared for visible-light-driven organic transformations. The 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine (pytz) derivative shows visible light absorption and reversible one-electron reduction behavior. In the presence of pytz and aerial oxygen, aldehyde reacts with o-phenylenediamine or o-aminothiophenol under visible light irradiation at ambient temperature to produce corresponding 2-substituted benzimidazoles and benzothiazoles, respectively. Pytz catalyst demonstrates excellent catalytic activity for alkyl, aryl, organo-metallic substituted aldehydes and reducing sugar. The reaction yield is high for both the electron-donating and electron withdrawing substituents in aromatic aldehydes. The use of a metal-free catalyst and visible light energy, along with the mild reaction conditions, makes this reaction an environmentally benign and energy-saving chemical process.
authors.affiliation: Department of Chemistry, Bengal Engineering and Science University , Shibpur, Howrah 711 103, West Bengal, India.
authors.forename: Suvendu
authors.initials: S
authors.lastname: Samanta
authors.forename: Sudipto
authors.initials: S
authors.lastname: Das
authors.forename: Papu
authors.initials: P
authors.lastname: Biswas