A Convenient Synthesis of 2H‐Pyran‐2‐ones, Fused Pyran‐2‐ones, and Pyridones Bearing a Thiazole Moiety

Abstract

in Wiley Online Library (wileyonlinelibrary.com).The versatile enaminonitrile, 2-cyano-3-(dimethylamino)-N-(4-phenylthiazol-2-yl)-acrylamide (2), reacts with some C,O-binucleophiles (acetylacetone and dimedone) in refluxing acetic acid to afford the pyranone 4, the chromene 6 derivatives, and with C,N-binucleophiles (2-(benzothiazol-2-yl)acetonitrile and 2-(1Hbenzimidazol-2-yl)acetonitrile) to afford the respective 1H-pyrido[2,1-b]benzothiazole 8 and pyrido [1,2-a]benzimidazole 10 derivatives. Similar treatment of 2 with phenol, resorcinol, a-naphthol and b-naphthol in boiling acetic acid gave the coumarin derivatives 12, 14, 16, and 18, respectively. The utility of enaminonitrile 2 for the synthesis of 6H-pyrano [3,2-d]isoxazole 20, pyrano[2,3-c]pyrazole 22, and pyrano[2,3-d]pyrimidine 24 derivatives was also explored via its reaction with 3-phenylisoxazol-5(4H)-one, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one, and barbituric acid, respectively. The mechanistic aspects for the formation of the new compounds were also discussed.

New One Pot-synthesis of Functionally Substituted Pyridines from Enaminoketones

“…The elaboration of efficient synthesis protocols for a variety of aromatic and heteroaromatic systems as potential bio‐active agents have been a major area of research interest in our laboratory over the past several years . Recently, enaminones have been successfully utilized as building blocks for the synthesis of polyfunctionalized heteroaromatics and other related condensed systems . In view of our interest in developing an efficient synthesis of polyfunctionally substituted heteroaromatics using the readily obtainable enaminoketones 1a , 1b , 1c , 1d as starting materials, it was worthwhile to explore their potential utilization for the synthesis of polyfunctional substituted pyridines because of their biological and medicinal activities.…”