Synthesis and Structure of Thia and Selena Heterocycles Containing Cycloamidine Substructures

Cyclization of a bis-arylimidoyl chloride with an acylselenourea leads to the construction of a 1,3-selenazolidine with a heteroradialene structure. Another reaction of the bis-arylimidoyl chloride (hydrazinolysis) leads to the formation of Δ2-1,2-diazetines, which we have shown previously to be reactive precursors for ring transformation reactions that yield unusual heterocycles. We now demonstrate that the reaction of these Δ2-1,2-diazetines with various isothio- or isoselenocyanates affords an efficient entry to highly substituted 1,3,4-thia- or -selenadiazines. The structures of these novel derivatives were confirmed by NMR and mass spectroscopy, elemental analysis, and X-ray structural analysis. Detailed multidimensional 77Se NMR experiments as well as density functional theory (DFT) calculations show structural specifics of these compounds.