Addition of Diazo Compounds ipso-C–H Bond to Carbon Disulfide: Synthesis of 1,2,3-Thiadiazoles under Mild Conditions

A Boron Scan of Ethyl Acetoacetate Leads to Versatile Building Blocks

Discovered in the 19th century, ethyl acetoacetate has been central to the development of organic chemistry, including its pedagogy and applications. In this study, we present borylated derivatives of this venerable molecule. A boron handle has been installed at either α ${{\rm \alpha }}$ - or β ${\beta }$ -position of acetoacetate by homologation of acyl-MIDA (N-methyliminodiacetic acid) boronates with diazoacetates. Either alkyl or boryl groups were found to migrate with regiochemistry being a function of the steric bulk of the diazo species. Boryl β ${{\rm \beta }}$ -ketoesters can be further modified into borylated pyrazolones and oximes, thereby expanding the synthetic toolkit and offering opportunities for additional modifications.

Base-promoted anaerobic intramolecular cyclization synthesis of 4,5-disubstituted-1,2,3-thiadiazoles

An alkali-promoted, transition-metal-free and oxidant-free method to construct 4,5-disubstituted-1,2,3-thiadiazoles from N-tosylhydrazone-bearing thiocarbamates by employing a sustainable intramolecular reaction strategy has been developed.

Synthesis of spiro[4.4]thiadiazole derivatives via double 1,3-dipolar cycloaddition of hydrazonyl chlorides with carbon disulfide

An operationally simple and convenient synthesis method toward a series of diverse spiro[4.4]thiadiazole derivatives via double [3 + 2] 1,3-dipolar cycloaddition of nitrilimines generated in situ from hydrazonyl chlorides with carbon disulfide has been achieved under mild reaction conditions.

Transition-metal-free synthesis of 5-amino-1,2,3-triazoles via nucleophilic addition/cyclization of carbodiimides with diazo compounds

A facile and transition-metal-free synthesis of functionalized 5-amino-1,2,3-triazoles with good functional-group tolerance and regioselectivity via nucleophilic addition/cyclization has been described.

I2/CuCl2-promoted one-pot three-component synthesis of aliphatic or aromatic substituted 1,2,3-thiadiazoles

An efficient I₂/CuCl₂-promoted one-pot three-component strategy for the construction of 1,2,3-thiadiazoles from aliphatic- or aromatic-substituted methyl ketones, p-toluenesulfonyl hydrazide, and potassium thiocyanate has been developed. Simple and commercially available starting materials, a broad substrate scope, and excellent functional group tolerability make this strategy practical for applications. Furthermore, 1,2,3-thiadiazole synthesis was realized by using potassium thiocyanate as an odorless sulfur source.