Au ııı-promoted cyclization reaction of ynoneoxime derivatives furnished 4H-1,2-oxazine ring under mild reaction conditions. When an alcohol is present in the reaction media, it was attached to the oxazine ring by the second activation of cyclic intermediate with a gold catalyst. Cholesterol, propargyl alcohol, phenol, and some of the different alcohol derivatives with alkyl chain were bonded to the oxazine ring in good yields. While amine derivatives did not attach to the ring under optimized reaction conditions, the molecule with the thiol group deactivated the gold catalyst under the same reaction conditions and did not give any cyclic products. With the obtained cyclization protocol, 11 unknown oxazine derivatives were synthesized and characterized. The proposed cyclization mechanism was drawn according to the two independent control experiments, DFT optimization, and NBO charges.
N-Propargyl-2-aroylimidazoles synthesized and converted into the corresponding ketoximes. Under various conditions, several mono- and diketoxime imidazole derivatives were formed by converting the carbonyl or carbonyl and propargyl groups into oxime groups. N-Propargyl monooxime imidazole derivatives were cyclized by treatment with CuI to give various imidazopyrazine N-oxides. Several copper salts, such as CuOAc, CuSO4, and CuOTf, formed the same cyclization product. This cyclization reaction occurred only in the presence of Cu(I) or Cu(II) salts; other transition metals such as Au, Ag, In, and Fe did not yield cyclic products. The nucleus-independent chemical shift method was used to calculate the aromaticity of the bicyclic rings.
Synthesis of pyrazole-3-carboxylic acid was progressed via two different protocols, one of
which is solid state. Pyrazole-3-carboxylic acid was converted into different derivatives such as ester,
urea, amide and nitrile. The amide compound was converted to nitrile using SOCl2 and DMF. Solid
state heating of carboxylic acid gave decarboxylated product. Cyclization of tetra-substituted pyrazole
with hydrazines resulted in pyrazolopyridazinones. The antimicrobial activities of the synthesized pyrazole
derivatives against Bacillus cereus, Escherichia coli, Micrococcus luteus, Staphylococcus aureus,
and Saccharomyces cerevisiae were evaluated. One of the pyrazole derivatives which possess nitro group
showed antimicrobial activity in only B. cereus, a Gram-positive bacteria, with an MIC of 128 μg/mL.
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