First Palladium‐Catalyzed Direct Regioselective C‐5 (Het)Arylation of Mono‐ or Disubstituted Thiazolo[3,2‐b][1,2,4]triazoles

Abstract

An efficient and convenient method was developed for the formation of polysubstituted thiazolo[3,2‐b][1,2,4]triazoles through C‐5 (het)arylation. The direct C–H activation protocol giving access to di‐ and trisubstituted derivatives in excellent yields was optimized. The method is suitable for use with a wide range of (hetero)aryl bromides, and allows access to a collection of C‐5,6 bis(het)aryl derivatives with full regioselectivity. The results are supported by a full description of all final compounds, and X‐ray crystallographic data confirmed that the spectroscopic analyses were interpreted correctly.

3-[(4-Phenoxyphenyl)sulfanyl]-5-phenyl-1H-1,2,4-triazole

“…Interestingly, working with sulfur-containing heterocycles may provide unexpected results and we report herein on the crystal structure of one derivative obtained within an unprecedented series of results (Ben Othman et al, 2014).…”

“…For the crystal structures of related N-free triazole derivatives, see for example : Qadeer et al (2007); and for N-subsituted derivatives, see for example: Zhao et al (2010); Wu et al (2009). Working with sulfur-containing heterocycles may provide unexpected results and the title compound was obtained within an unprecedented series of results, see: Ben Othman et al (2014).…”

Fused bicyclic 1,2,4‐triazoles with one extra sulfur atom: Synthesis, properties, and biological activity

“…1,3-dipolar cycloaddition of hydrazonoyl chlorides to the C‚N bond of 1,5-benzothiazepines in water in the presence of Na 2 CO 3 / (TEA)THAC as the main catalyst lead to the formation of 1,2,4-triazolo[3,4-d] [1,5]benzothiazepines 48 (Scheme 36). [98] 7 | CHEMICAL PROPERTIES OF BICYCLIC 1,2,4-TRIAZOLES WITH ONE EXTRA SULFUR ATOM triazoles with aryl halides [99][100][101][102][103] or sodium salt of arylsulfonic acid [104] was carried out under different conditions. These techniques have been successfully applied to the synthesis of 5-substituted thiazolo[3,2-b][1,2,4] triazoles 49 in high yields (Scheme 37).…”

Synthesis of novel series of 3,5-disubstituted imidazo[1,2-d] [1,2,4]thiadiazoles involving SNAr and Suzuki–Miyaura cross-coupling reactions

“…For several years, our group has disclosed efficient methodologies to selectively functionalize bicyclic [5,5] heterocycles such as [1,2,4]triazolo[3,4- b ][1,3,4]thiadiazoles, 20 thiazolo[3,2- b ][1,2,4]triazoles 21 and more specially, imidazo[2,1- b ][1,3,4]thiadiazoles. 22–26 The latter have proven applicable to the discovery of a wide variety of biological molecules.…”