Expeditive Access to 2-Substituted 4H-Pyrido[1,3]oxazin-4-ones via an Intramolecular O-Arylation
摘要:
Unreported 2-substituted 4H-pyrido[e][1,3]oxazin-4-ones are synthesized via an unprecedented intramolecular O-arylation of N-aroyl- and N-heteroaroyl-(iso)nicotinamides under microwave irradiations, in good to excellent yields. The broad applicability was demonstrated by 24 examples with a variety of substituents at the 2-position of the final compounds and 3 possible positions for the nitrogen atom of the pyridine ring. In addition, transformation of one of these compounds into 2-hydroxypyridyl-substituted 1,2,4-triazole and 1,2,4-oxazinone was realized. This approach opens a rapid access to a new bicyclic heteroaromatic chemical series with high potential in medicinal chemistry.
Chemoselective Access to π-Conjugated Heterocycles by Stille and Sonogashira Reactions on 2-Substituted 4<i>H</i>-Pyrido[<i>e</i>][1,3]oxazin-4-ones
作者:Laetitia Le Falher、Amara Mumtaz、Anthony Nina Diogo、Serge Thorimbert、Candice Botuha
DOI:10.1002/ejoc.201601338
日期:2017.1.26
Site-selective PdII-catalyzed cross-coupling reactions of 2-substituted-4H-pyrido[e][1,3]oxazin-4-ones were developed. C4and C5-alkynylated pyridooxazinones were thus obtained through Sonogashira coupling, whereas the efficient incorporation of (hetero)aryl and ethenyl substituents at the C5 position was achieved by Stille coupling. Finally, an example of