Visible light promoted formation of N─S bond by photocatalyst Eosin Y

Abstract

A novel efficient protocol for the synthesis of 5‐imino‐1,2,4‐thiadiazole motif in open air and visible light has been reported. The reaction involves Eosin Y as photocatalyst which is a cost‐effective organic dye. The designed protocol represents a novel, mild, metal free, green strategy for the construction of 1,2,4‐thiadiazole nucleus by intramolecular cyclization via N─S bond formation. The reaction has been carried out under visible light exposure in ethanol: water (4:1) mixture using 2‐aminopyridine and isocyanate as reactants.

Directed evolution of Escherichia coli surface-displayed Vitreoscilla hemoglobin as an artificial metalloenzyme for the synthesis of 5-imino-1,2,4-thiadiazoles

“… 10 Siddiqui et al employed a visible light-promoted formation of the S–N bond for the synthesis of the 5-imino-1,2,4-thiadiazole motif in EtOH : H 2 O (4 : 1) at room temperature ( Scheme 1e ). 11 However, some drawbacks exist, such as the use of high temperature, harmful organic solvents, or the limitation of the substrate scope. Therefore, exploring eco-friendly, green, and efficient strategies that have not yet been realized should be given importance when constructing these valuable and highly attractive 5-imino-1,2,4-thiadiazole structures.…”

Chemodivergent Synthesis of Benzothiadiazin-3-one 1-Oxides and Benzisothiazol-3-ones via Visible Light-Promoted Intramolecular N–S Bond Formation

“…14 However, the visible light-promoted N−S bond formation is still less explored. 15 With our continuous studies on the synthesis of sulfur-containing heterocycles and visible light photocatalysis, 16 herein, we would like to present a visible light-promoted chemodivergent synthesis of benzothiadiazin-3-one 1-oxides and benzisothiazol-3-ones through intramolecular N−H/S−H dehydrogenative oxidative coupling reactions (Scheme 1d). Notable features of our findings include (i) readily accessible 1 as substrates, the benzothiadiazin-3-one 1-oxide products 2 were obtained without the formation of cyclic sulfenamide or sulfonamide byproducts; (ii) 3 as substrates, the only benzisothiazol-3-one products 4 were afforded through the formation of cyclic sulfenamides; and (iii) mild conditions, excellent chemoselectivity, and broad functional group compatibility.…”

Synthesis and Antimicrobial Evaluation of Some Novel Pyrido[2,3‐d] Pyrimidine Derivatives and Their Ribofuranosides

“…The ribofuranosides of pyrido[2,3‐ d ]pyrimidines have been reported as antileukemic , anti‐AIDS , antiherpes , hypnotic activity , and so forth. Some new pyrido[2,3‐ d ]pyrimidines and their ribofuranosides have been synthesized in our previous laboratory work, which showed varying degrees of antimicrobial activity . The manifold applications of pyrido[2,3‐ d ]pyrimidines and their ribofuranosides have prompted us to target the synthesis of some novel 4‐imino‐3,5,7‐trisubstituted pyrido[2,3‐ d ]pyrimidin‐2‐(1 H )‐ones and 4‐imino‐3,5,7‐trisubstituted pyrido[2,3‐ d ]pyrimidin‐2‐(1 H )‐thiones and their ribofuranosides 7a–c and 8a–c .…”