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Amino-1,5-benzoxazepines 2 and 5 and hydroxyl-1,5-benzodiazepines 3 and 6 have been synthesized in one-pot solvent-free conditions from 2,3-diaminophenol and ketones through microwave assisted acid catalysis, the benzoxazepine/benzodiazepine ratio depending on the R(1) and R(3) aryl substituents. The otherwise inaccessible and unknown 2,2-dimethyl-4-aryl-1,5-benzodiazepines 8 were also prepared in an analogous manner. The reaction mechanism was investigated by means of DFT calculations. Structural assignments of the new compounds as well as complete assignment of (1)H and (13)C NMR signals have been unambiguously achieved on the basis of the analysis of their (1)H and (13)C NMR (1D and 2D), IR, MS, and elemental analysis data, whereas the presence of an amino group in 5 and of a hydroxyl in 6 was confirmed by derivatization. Compounds 2, 3, 5f, 6a, 6c, 6d, 6f, 6h, 8c, and 12 were evaluated as antioxidants and lipid peroxidation inhibitors in vitro. Compound 6f was also evaluated as anti-inflammatory agent in vivo. Compounds 2 and 6f were found to be the most potent as inhibitors of lipoxygenase and of lipid peroxidation, respectively.

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Another aspect concerning chromone chemistry leading to the one-pot synthesis of functionalized novel spirobenzofuranones has been described. The synthesis involves reaction of the zwitterionic intermediates formed by the 1:1 interaction between isocyanides and acetylenecarboxylates with 3-cyanochromones, whereupon through an unexpected and unprecedented reaction of the chromone moiety the isolated benzofuranones are formed. The regioselectivity of the reaction was investigated by DFT calculations. The geometries of the intermediates, transition structures, and intermediate products, leading to the final products, were optimized using the B3LYP functional with the 6-31G(d) basis set. The structures of the products were elucidated by 1D and 2D NMR experiments. Full assignment of all (1)H and (13)C NMR chemical shifts has been achieved. A plausible mechanistic rationale is proposed.

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The reaction of 1:1 zwitterionic intermediates generated in situ from either tert-butylisocyanide or cyclohexylisocyanide and acetylenedicarboxylates with 3-formylchromones is described, whereupon either chromenylfurandicarboxylates or cyclopenta[b]chromenedicarboxylates are formed, depending on the nature of the chromone 6-position substituent and also on the acetylene ester group. In addition, from the reaction with a 1:2 zwitterionic intermediate, cyclohepta[b]chromenetetracarboxylates are isolated. The regioselectivity of the reaction was also investigated by DFT calculations. The geometries of the reactants, intermediate zwitterions, transition structures, and intermediate products, leading to the final products, were optimized using the B3LYP functional with the 6-31G(d) basis set. The structures of the products were elucidated by 1D and 2D NMR experiments. Full assignment of all (1)H and (13)C NMR chemical shifts has been achieved. Plausible mechanistic schemes are provided.

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