A Facile Route to Imidazo[1,2-a]quinolines via a Domino Reaction

The interaction of methyl 2,4-dioxo-2H-3,1-benzoxazine-1(4H)-acetate, 1-(3,3-dimethyl-2-oxobutyl)- and 1-(2-oxopropyl)-2H-3,1-benzoxazine-2,4(1H)-diones with substituted acetonitriles, XCH₂CN (X = CN, hetaryl), has been studied. In acetic acid in the presence of sodium acetate, imidazo[1,2-a]quinoline-2,5(1H,3H)-diones, 2-tert-butyl- and 2-methylimidazo[1,2-a]quinolin-5(3H)-ones were obtained in 60-85% yield. A reaction pathway is suggested and has been confirmed by the isolation of specific intermediates. The scope and limitations of the method are discussed. The structure of the obtained imidazo[1,2-a]quinoline derivatives has been assigned unambiguously on the basis of an X-ray crystallographic study.

Iminov R. T.; Tverdokhlebov A. V.; Tolmachev A. A.; Volovenko Y. M.; Kostyuk A. N.; Chernega A. N.; Rusanov E. B.
Synthesis 2008, 10, 1535-1540
DOI: 10.1055/s-2008-1072572