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Aerobic, metal-free synthesis of 6H-chromeno[4,3-b]quinolin-6-ones

Author:
Ton, Nhan N. H., Dang, Ha V., Phan, Nam T. S., Nguyen, Tung T.
Source:
RSC advances 2019 v.9 no.28 pp. 16215-16222
ISSN:
2046-2069
Subject:
acetic acid, acetophenones, oxidants, oxygen, quinolones, solvents
Abstract:
A Friedländer-based method for transition-metal free, aerobic synthesis of chromene-fused quinolinones is reported. The coupling of 4-hydrocoumarins and 2-aminobenzyl alcohols proceeds in the presence of acetic acid solvent and oxygen oxidant, affording 6H-chromeno[4,3-b]quinolin-6-ones in good to excellent yields. The reactions are tolerant of functionalities such as alkyl, methoxy, bromo, chloro, and N-heterocycle. Isosteric cyclic 1,3-diketones and 2-amino acetophenones also give fused quinolinones under reaction conditions. The method herein offers a rapid and benign synthesis of hitherto challenging N-heterocycles. To our best knowledge, such a convenient pathway to obtain chromene-fused quinolinones have not been known in the literature.
Agid:
6458883