Structural revision in the reactions of 3-cyanochromones with primary aromatic amines. Improved synthesis of 2-amino-3-(aryliminomethyl)chromones

Reactions of 3‐Acylchromones with Heterocyclic Ketene Aminals: One‐Pot Synthesis and Phosphatase Inhibitory Activity of Fused Pyridine Derivatives

“…Furthermore, chromones have been shown to be important building blocks . In the last decades, 3‐substituted chromones,, such as 3‐formylchromone, have attracted attention, due to their high density of electrophilic centers, which give rise to cascade reactions with nucleophiles. Their reactions usually proceed by initial nucleophilic 1,4‐addition at the most electron‐deficient carbon atom located at the 2‐position, followed by opening of the γ‐pyrone ring.…”

Chemical Transformations of Chromone‐3‐carbonitrile with Cyclohexanediones: Synthesis of Bis[1]chromenophenanthrolines

“…Chromone-3-carbonitriles acquire the ability to undergo a nucleophilic 1,4-attack followed by additional transformations related to γ-pyrone ring opening and heterocyclizations at the C-4 atom and/or at the cyano group. Several 5-oxo-chromeno[2,3-b]pyridine derivatives, obtained from condensation of chromone-3-carbonitrile 1 with some active methylene compounds [5][6][7][8][9], have received increased attention because of their medicinal applications particularly as antiallergic and antiulcer drugs [10][11][12][13][14]. Herein, we aimed to study the chemical reactivity of chromone-3-carbonitrile (1) toward 1,2-cyclohexanedione, 1,3-cyclohexanedione, and 1,4cyclohexanedione under different reaction conditions.…”

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

“…Because these data contradicts the results obtained above for the reaction of 3-cyanochromones with anilines, we have studied the structure of the reaction products of chromones 1a-c with o-phenylenediamine by 1D and 2D NMR spectroscopic methods. It was found that compounds 8a and 10a have the 2-aminochromon-3-imine structure 11a, similar to the chromones 6 [7]. Hence the adducts 9a-c cyclize via addition of the phenolic hydroxyl at the cyano group and not the amino group.…”

“…Hence the adducts 9a-c cyclize via addition of the phenolic hydroxyl at the cyano group and not the amino group. Refluxing compounds 11a-c in AcOH gives the previously reported 3-(benzimidazol-2-yl)-chromones 12a-c [10,11], the possible formation mechanism of which has been given in [7].…”

“…The tautomers 4'a-c, 5a-c, and 6'a-c were not observed [7,8]. The product composition of the non-catalyzed reaction of the 3-cyanochromones 1 with aromatic amines depends markedly on the nature of the substituent in position 6 of the chromone and to a lesser degree on the substituent in the aniline residue.…”