Reactions of 3-cyanochromones with primary amines: structures of the products

Abstract

Reactions of 3 cyanochromones with primary aromatic amines in boiling benzene gave mixtures of Z and E 3 arylamino 2 (2 hydroxyaroyl)acrylonitriles and 2 amino 3 (aryl iminomethyl)chromones. The latter can easily be obtained in the individual state when the reaction is carried out in the presence of triethylamine. In the case of primary aliphatic amines, the open chain reaction product immediately undergoes cyclization into 3 alkyliminomethyl 2 aminochromones. The structures of the products were examined by 1D and 2D 1 H, 13 C, and 15 N NMR spectroscopy in DMSO d 6 and CDCl 3 .

Chemistry of 4-oxo-4H-1-benzopyran-3-carbonitrile

“…26 A mixture of ChrCN and N,N-dimethylhydrazine in refluxing benzene forms the hydrazone 51 that in DMF heated under reflux undergoes self-condensation to the diazocene 27. …”

Novel data for the reaction of 3-cyano-(thio)chromones with N-nucleophiles

“…We have shown [19] that this reaction occurs as a nucleophilic 1,4-addition accompanied by opening of the pyrone ring (intermediate F) and subsequent recyclization to hydrazones 26a-c or 5-aminopyrazoles 27a,b depending on the conditions used. The structures of compounds 26 and 27 were strictly proved from their 2D HSQC and HMBC spectra.…”

“…Chromones 1a-c react differently with methylhydrazine (refluxing in benzene for 0.5 h) to give the pyrazoles 30a-c in moderate yield but with high regioselectivity [19]. In this case the reaction begins with a nucleophilic attack by the substituted nitrogen atom at C-2 atom of the starting molecule (intermediate G) and subsequent intramolecular cyclization at the carbonyl group.…”

“…In this case the reaction begins with a nucleophilic attack by the substituted nitrogen atom at C-2 atom of the starting molecule (intermediate G) and subsequent intramolecular cyclization at the carbonyl group. Under more rigorous conditions (refluxing in acetic acid for 5 h) the 4-cyanopyrazoles 30a-c cyclize to the coumarins 31a-c and these can also be obtained directly from the chromones 1a-c and methylhydrazine [19].…”

Synthesis of New Quinolinones from 3-Nitropyranoquinolinones

“…3-Substituted-γ-pyrones are valuable synthetic intermediates in the preparation of new heterocyclic systems and many biologically important substituted quinolinones. [1][2][3][4][5][6] Recently, quinolinone derivatives have become of increasing interest since many of these compounds show useful applications as chemotherapeutic agents. For example, some quinolinones were recently reported to have potential as inhibitors for hepatitis C polymerase, 7,8 microsomal prostaglandin E2 synthase-1 and selective ions.…”