Studies with enaminones: synthesis of new coumarin-3-yl azoles, coumarin-3-yl azines, coumarin-3-yl azoloazines, coumarin-3-yl pyrone and coumarin-2-yl benzo[b]Furans

✍ Scribed by Fathy Mohamed Abel Aziz El-Taweel; Mohamed Hilmy Elnagdi

• Publisher: Journal of Heterocyclic Chemistry
• Year: 2001
• Tongue: English
• Weight: 48 KB
• Volume: 38
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570380428

✦ Synopsis

Abstract

3‐Acetylcoumarine was condensed with dimethylformamide dimethylacetal (DMFDMA) to yield the enaminone, which reacts readily with hydroxylamine and with hydrazines to yield coumarin‐3‐ylisoxazoles and coumarin‐3‐ylpyrazoles respectively. Reaction of the enaminone with benzamidine hydrochloride and 3‐amino‐1,2,4‐1__H__‐triazole affords the pyrimidine and triazolo[3,4‐b]pyrimidine. The enaminone reacts with hippuric acid and with the dithiocarboxylic acid to yield pyranones. The reaction of the enaminone with 3‐amino‐1__H__‐1,2,4‐triazole gives the triazolo[3,4‐b]pyrimidine. The enaminone underwent self dimerization on reflux in acetic acid ammonium acetate to yield the coumarinyl pyridines and reacted with ketone under the same conditions to yield the pyridine. The reaction of the enaminone with 1,4‐benzoquinone and 1,4‐naphthoquinone gives benzofuryl coumarine derivatives.