Iron-Catalyzed Green Synthesis of 2-Alkenylazaarenes
Sensheng Liu, Kun Jiang, Danwei Pi, Haifeng Zhou, Yasuhiro Uozumi, Kun Zou · Chinese Journal of Organic Chemistry · 2014
A straightforward and selective synthesis of bioactive trans-2-alkenylazaarenes has been achieved via cheap and nontoxic iron(II) acetate catalyzed addition and dehydration reactions of 2-methylazaarenes and aromatic aldehydes in the presence of catalytic amount of trifluoroacetic acid with water as the only byproduct.The low catalyst loading, convenience, good yield, high selectivity, as well as the broad substrate scope make this protocol very practical.The practical potential was also demonstrated by gram-scale synthesis of (E)-3-[2-(7-chloro-2-quinolinyl)ethenyl]benzaldehyde (3v), an intermediate of Singulair.