Microwave-accelerated multicomponent synthesis and X-ray characterization of novel benzothiadiazinone dioxide derivatives, analogues of Monastrol

We demonstrate here a rapid and comfortable synthetic sequence to benzothiadiazinone dioxide (six-membered cyclic sulfamide) derivatives, analogues of Monastrol, which is known to be a specific mitotic kinesin Eg5 inhibitor. Fourteen novel compounds (1d–14d) were synthesized through three component Biginelli reaction, by condensation of aromatic aldehyde, sulfamide, and cyclohexane-1,3-dione. A wide range of substrates is compatible in this reaction, producing excellent yields (82–92%) in short time (5–10 min). The reaction is performed under solvent-free, catalysed by H2SO4/CH3COOH (1/9) using microwave irradiation. The structure of the obtained substances was confirmed by 1H, 13C, HMBC, HSQC NMR spectroscopy, IR spectroscopy, and mass spectrometry, as well as elemental analysis. A single crystal of the (4-phenyl-4,6,7,8-tetrahydro-1H benzo[c][1,2,6]thiadiazin-5(3H)-one 2,2-dioxide has been obtained after recrystallization in ethanol/acetone (9/1) and selected for X-ray study.