RESUMO
Synthesis of 3-acetyl-6-substituted coumarin la-c have been carried out. The reaction of 3-aeetyl-6-broniocoumarin 1b with ethyl oxalate in the presence of sodium metal afforded the corresponding 3-coumarinyl pyruvic acid derivative 2, which converted into corresponding thiazole derivatives 3. The condensation of 1a. b with thiourea in the presence of bromine afforded imidazole derivatives 4a. b and aminothiazole derivatives 5a. b. The reaction of 1e with KCN yielding carboxylic acid amide derivative 6, which converted into the corresponding pyridazine derivative 7 on treatment with hydrazine hydrate. Compound 1e condensed with malononitrile afforded ethylidene malononitrile derivative 8 and coumarinoyl ethylenyl coumarin derivative 9. While compound 1e condensed with 3- iminobutyronitrile gave pyridonaphthopyranone 10 and 9. Stirring cold solution of 1e with bromine in acetic acid to give the corresponding bromide derivative 11, which converted into propionitrile derivative 12, when refluxed when KCN solution. Also, compound 11 condensed with 3-iminobutyronitrile gave pyrrolopyridine derivative 13. Compound 12 coupled with phenyl diazonium chloride to afford acyclic azohydrazone derivative 14. Compounds 1a-e readily condensed with aromatic aldehydes to give 3-[substituted cinnamoyl]-coumarin derivatives 15a, b. The reaction of 15a with methyl isopentyl ketone in the presence of sodium acetate yielded pyridocoumarin derivative 16. The reaction of 15b with active methylene compounds namely ethyl acetoacetate, malononitrile, ethyl cyanoacetate and/or diethyl malonate in the presence of ammonium acetate gave corresponding pyronyl coumarin derivatives 17-19 respectively