Silver Phosphotungstate: A Novel and Recyclable Heteropoly Acid for Friedländer Quinoline Synthesis
J. S. Yadav*, B. V. S. Reddy, P. Sreedhar, R. Srinivasa Rao, K. Nagaiah
*Division of Organic Chemistry, Indian Institute of Chemical Technology,
Hyderabad-500 007, India, Email: yadav
iict.res.in
J. S. Yadav, B. V. S. Reddy, P. Sreedhar, R. S. Rao, K. Nagaiah, Synthesis, 2004, 2381-2385.
DOI: 10.1055/s-2004-831185
Abstract
o-Aminoaryl ketones undergo a smooth, mild and selective condensation with α-methylene ketones on the surface of silver heteropoly acid (Ag3PW12O40) to afford the corresponding polysubstituted quinolines in excellent yields. The catalyst can be recovered by simple filtration and can be recycled.
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Details
The document discusses the use of silver phosphotungstate (Ag3PW12O40) as a novel and recyclable heteropoly acid catalyst for the Friedländer synthesis of quinolines. This method involves the condensation of o-aminoaryl ketones with α-methylene ketones under mild conditions, yielding polysubstituted quinolines with high selectivity and excellent yields. The catalyst can be easily recovered by filtration and reused with minimal loss of activity, making the process economically viable and environmentally friendly. The study highlights the advantages of using solid acids over conventional homogeneous acid catalysts, including ease of recovery, reusability, and cleaner reaction profiles. The method is effective for both cyclic and acyclic ketones and does not require high temperatures or strong acids, unlike traditional methods. The products were characterized using various spectroscopic techniques, and the method was found to be superior to other solid acids like K10 clay, SiO2, and HZSM-5. This approach offers a simple, efficient, and environmentally benign route for synthesizing highly functionalized quinolines, which are important in pharmaceuticals and other applications.
Key Words
heteropoly acids, o-aminoaryl ketones, α-methylene ketones, quinolines, Friedländer synthesis
ID: J66-Y2004-2350
