Facile preparation of 3-functional chromen-2-ones

ABSTRACT

The reaction of 3-carbethoxy-chromen-2-one [1] with thiosemicarbazide in pyridine afforded 3-[5-sulphonyl-2H-[1, 2, 4] triazol-3-yl]-chromen-2-one [2]. The alkylation of compound 2 with methyl iodide, ethyl chloroformate and ethyl bromoacetate in dry acetone gave the corresponding alky lated product 3a-c, respectively. The thiol group was readily substituted by various nitrogen nucleophiles such as hyurazine hydrate. urea and thiourea and primary amines gave the hydrazino-derivative 4, urea and thiourea derivatives 6a and 6b and amino-derivatives 7a-c. The hydrazino-derivative 4 was converted to triazolo [4, 3-b] triazolo-6-yl chromen-2-one derivatives 5a and 5b when refluxed with formic and acetic acid. The addition of thiol group in compound 2 to maleic and phthalic anhydrides was carried to give succinic and benzoic acid derivatives 8 and 10, respectively, which condensed with hydrazine hydrate to give the corresponding pyridazine derivative 9 and phthalazine derivative 11, respectively. The reaction between compound 2 and aroylacrylic acid derivatives afforded the corresponding 12a and 12b derivatives. Refluxing 12b in acetic anhydride yielded the furan derivative 13. Compounds 12b and 13 were converted to pyridazine derivative 14