Synthesis and Structures of 3-Aryl-6-methyl-1,6-dihydro-1,2,4,5-tetrazines and Their Derivatives

A convenient and effective method was developed from the starting materials acetonitrile and aryl nitrile via three steps to synthesize 3-aryl-6-methyl-1,6-dihydro-1,2,4,5-tetrazines. On the basis of which, some 3-aryl-6-methyl-1,6-dihydro-1,2,4,5-tetrazine derivatives were synthesized and characterized by elemental analysis, H-1 NMR, IR and HRMS techniques. The X-ray single crystal diffraction study of 6-methyl-3-phenyl-N-(2-tolyl)-1,6-dihydro-1,2,4,5-tetrazine-1-carboxamide (5a) indicates that 5a belongs to a monoclinic system, with a=1.3941(6) nm, b=05675(2) nm, c=2.0614(8) nm; alpha=gamma=90 degrees, beta=102.055(6)degrees; V=1.5949(11) nm(3). The central tetrazine ring adopts an unsymmetrical boat structure It could be considered that the molecule had a homoaromaticity.