TBAI-Catalyzed Reaction between <i>N</i>‑Tosylhydrazones and Sulfur: A Procedure toward 1,2,3-Thiadiazole

A TBAI-catalyzed reaction between <i>N</i>-tosyl hydrazone and sulfur was developed, leading to 1,2,3-thiadiazoles in moderate to good yields. It represents a facile and practical procedure to access thiadiazole under metal-free conditions. This procedure serves as an improvement for the Hurd–Mori reaction

Multicomponent Coupling Reactions of Two <i>N</i>‑Tosyl Hydrazones and Elemental Sulfur: Selective Denitrogenation Pathway toward Unsymmetric 2,5-Disubstituted 1,3,4-Thiadiazoles

A copper-mediated, three-component reaction between two different <i>N</i>-Ts hydrazones and elemental sulfur was developed, leading to a series of unsymmetric 2,5-disubstituted 1,3,4-thiadiazoles in moderate yields with good functional group compatibility. This procedure features the employment of elemental sulfur and the selective denitrogenation between aryl and alkyl aldehyde <i>N</i>-tosyl hydrazones, allowing rapid access to unsymmetric 2,5-disubstituted 1,3,4-thiadiazoles frameworks with chemical diversity and complexity

1,3-Dipolar Cycloadditions of 4‑Acetoxy Allenoates: Access to 2,3-Dihydropyrazoles, 2,3-Dihydroisoxazoles, and Indolizines

The thermal 1,3-dipolar cycloadditions of 4-acetoxyallenoates <b>1</b> with various dipoles have been reported. When azomethine imines and nitrones are used as the 1,3-dipole partner, the corresponding reactions afford 2,3-dihydropyrazole and 2,3-dihydroisoxazole derivatives, respectively. These reactions might proceed via a thermal 1,3-dipolar cycloaddition and the subsequent elimination of HOAc. In addition, allenoates <b>1</b> react well with in situ generated azomethine ylides in which a similar cycloaddition pathway is followed by oxidative aromatization to give indolizine derivatives