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

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

The first access to 3,5-disubstituted imidazo[1,2-d][1,2,4]thiadiazole derivatives is reported. The series were generated from 2-mercaptoimidazole, which afforded the key intermediate bearing two functional positions. The S_NAr reactivity toward tosyl release at the C-3 position was investigated and a regioselective electrophilic iodination in C-5 position was performed to allow a novel C–C bond using Suzuki–Miyaura reaction. Palladium-catalyzed cross-coupling conditions were optimized. A representative library of various boronic acids was employed to establish the scope and limitations of the method. To complete this methodological study, the influence of the nature of the C-3 imidazo[1,2-d][1,2,4]thiadiazole substitutions on the arylation in C-5 was investigated.

A convenient design of 3,5-disubstituted imidazo[1,2-d][1,2,4]thiadiazoles is reported from 2-mercaptoimidazole, which afforded a versatile platform that was then used to access a variety of original heterocycles.

Design of selective COX-2 inhibitors in the (aza)indazole series. Chemistry, in vitro studies, radiochemistry and evaluations in rats of a [18F] PET tracer

A series of novel derivatives exhibiting high affinity and selectivity towards the COX-2 enzyme in the (aza) indazole series was developed. A short synthetic route involving a bromination/arylation sequence under microwave irradiation and direct C–H activation were established in the indazole and azaindazole series respectively. In vitro assays were conducted and structural modifications were carried out on these scaffolds to furnish compound 16 which exhibited effective COX-2 inhibitory activity, with IC₅₀ values of 0.409 µM and an excellent selectivity versus COX-1. Radiolabeling of this most potent derivative [¹⁸F]16 was achieved after boron ester release and the tracer was evaluated in vivo in a rat model of neuroinflammation. All chemistry, radiochemistry and biological experimental data are discussed.

[1,3]Thiazolo[3,2-b][1,2,4]triazol-7-ium salts: synthesis, properties and structural studies

The reactions of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium salts with nucleophiles were investigated. Theoretical investigation of reactivity descriptors and structural parameters of [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium cation was carried out, and the reactivity centers of the model salts were located. An efficient general method for the synthesis of novel poly-functional derivatives of symmetric triazoles from [1,3]thiazolo[3,2-b][1,2,4]triazol-7-ium halides was developed. The structures of the synthesized compounds were confirmed using proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), Fourier-transform infrared spectroscopy (FTIR) and single-crystal X-ray analysis.

A comparative theoretical study on energetic substituted 1,2,3- and 1,2,4-triazoles: the azido-cyclization mechanism and the effect of solvent

The azido-cyclization of 4,5-diazido-1,2,3-triazole and 3,5-diazido-1,2,4-triazole and the effect of solvent have been investigated using the hybrid DFT at the B3LYP/6-311G* level.

Advances in direct C–H arylation of 5,5- 6,5- and 6,6-fused-heterocycles containing heteroatoms (N, O, S)

This report aims to review the advances made in C–H arylation of 5,6, 6,6 and 5,5 fused-heterocyclic systems.

3-[(4-Phen-oxy-phen-yl)sulfan-yl]-5-phenyl-1H-1,2,4-triazole

The title compound, C₂₀H₁₅N₃OS, is V-shaped. In the 4-phen­oxy­phenyl group, the two rings are inclined to one another by 74.52 (13)°. These rings are inclined to the triazole ring by 72.20 (15) and 72.30 (15)°, respectively. The phenyl ring is inclined to the triazole ring by 10.85 (12)°. In the crystal, mol­ecules are linked via N—H⋯N hydrogen bonds, forming chains propagating along [010]. These chains are linked via pairs of C—H⋯S hydrogen bonds, forming sheets lying parallel to the ac plane.