Structural Investigation of 5-hydrazono-5,6,7,8-tetrahydro-2H-1-benzopyran-2-ones and 5,6,7,8-tetrahydroquinoline-2,5(1H)-diones

Substituted 2H-1-benzopyran-2-ones are useful synthons and have potential as biologically active compounds. In order to characterize the transformation of benzopyran-2,5 diones with a heterocyclic hydrazine to 2H-1-quinoline-2,5-diones and 5-hydrazono-2H-1-benzopyran-2-ones we have studied structural parameters of the products using 2D NMR techniques in solution combined with computational tools. Molecular modeling based on experimentally determined NOE distance restraints enabled determination of solution structures of two compounds: N-[1,2,5,6,7,8-hexahydro-1-[(imidazo[1,2-b]pyridazin-6-yl)amino]-7-methyl-2,5-dioxo-3-quinolinyl]benzamide and N-[5,6,7,8-tetrahydro-5-[(imidazo[1,2-b]pyridazin-6-yl)hydrazono]-7-methyl-2-oxo-2H-1-benzopyran-3-yl]benzamide.