Competitive intramolecular nucleophilic aromatic substitution: a new route to coumarins
作者:Concepción Alonso、Marilyn M. Olmstead、Michael H. Nantz、Mark J. Kurth
DOI:10.1039/b009172n
日期:——
4-Hydroxy-3-(2′-pyridyl)coumarins (4) (R = 6-Cl, H, 6-NO2, 8-NO2) were prepared in moderate to good yields by the intramolecular nucleophilic aromatic substitution reaction of β-ketoesters (I) in refluxing xylenes; evidence for the reversible formation of benzo[c]quinolizinium III from I (X = 4-Cl), with eventual formation of 4 (R = 6-Cl), is also presented.
4-Hydroxy-3-(2'-pyridyl)coumarins (4) (R = 6-Cl, H, 6-NO2, 8-NO2) 通过 β- 的分子内亲核芳族取代反应以中等至高产率制备回流二甲苯中的酮酯 (I);还提供了从 I (X = 4-Cl) 可逆地形成苯并 [c] 喹啉 III 并最终形成 4 (R = 6-Cl) 的证据。