Conventional and microwave-assisted solvent-free synthesis of fused [1,2,5]thiadiazolo[3,4-b]quinoxaline-2,2-dioxide derivatives

A simple, highly efficient and environmentally friendly procedure for the condensation of $o$-phenylenediamine with 2,5-dialkyl-1,2,5-thiadiazolidine-3,4-dione-1,1-dioxides via two microwave-assisted reactions is described. These compounds were also prepared via a conventional heating method to provide a comparison with the microwave-assisted irradiation reaction protocol. The structures of the synthesized compounds were confirmed using infrared, ¹H NMR and mass spectral analysis.