Chromeno chromone

Hydrazine hydrate reacts with ethyl chromone-2-carboxylate to give a hydrazide whose structure was at first believed to be a chromeno[2,3-d]pyra-zoline (57 or 58) [13] this structural assignment was based on infrared... 

Reactions of chromones 230 with acetoacetamide and ethyl acetoacetate in ethanol in the presence of ammonium acetate proceed at the C-2 atom of the chro-mone system with pyrone ring-opening and subsequent cycUzation to 252. Similar reaction with p-aminocrotononitrile gave 5-hydroxy-2-methyl-5-(polylluoroalkyl)-5ff-chromeno[4,3- ]pyridine-3-carbonitriles (253a) [129]. Three-component reaction between chromones 230, dimedone, and AcONH, is accompanied by detrifluoroacetylation and leads to 254 in low yields [130] (Schane 82). 

Potassium carbonate Chromeno [3,4-b] chromon es Selective replacement of alcohol groups by bromine... 

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