An unprecedented TfOH-promoted tandem ring-closure-aryl-migration of 2′-amino chalcone epoxide leading to 3-aryl-4(1H)-quinolones (azaisoflavones) was achieved. The outcome of the reaction was confirmed by NMR analysis and rationalized through the intermediacy of a phenonium ion. This synthetic protocol furnishes azaisoflavones straightforwardly from simple starting materials under mild conditions.
Fabrication of a synthetic azaisoflavone skeleton from 2'-nitrochalcone was done using oxidative rearrangement with a hypervalent iodine reagent. A key intermediate compound, aminoacetal, was prepared from readily available 2'-nitrochalcone via a PhI(OH)OTs-mediated rearrangement, followed by reduction of the nitro group. A variety of azaisoflavones were obtained in moderate to high yields by treatment of the intermediate compound under acidic conditions.
Praveen; Parthasarathy; Kumar, P. Senthil, Indian Journal of Chemistry - Section B Organic and Medicinal Chemistry, 2015, vol. 54B, # 3, p. 373 - 382
作者:Praveen、Parthasarathy、Kumar, P. Senthil、Perumal