Phosphane-Catalyzed Knoevenagel Condensation: A Facile Synthesis of α-Cyanoacrylates and α-Cyanoacrylonitriles
Jhillu S. Yadav *, Basi V. Subba Reddy, Ashok K. Basak, Boddapati Visali, Akkirala Venkat Narsaiah, Kommu Nagaiah
*Division of Organic Chemistry, Indian Institute of Chemical Technology,
Hyderabad-500 007, India, Email: yadavpub
iict.res.in
J. S. Yadav, B. S. S. Reddy, A. K. Basak, B. Visali, A. V. Narsaiah, K. Nagaiah, Eur. J. Org. Chem., 2004, 546-551.
DOI: 10.1002/ejoc.200300513
Abstract
Triphenylphosphine is an efficient catalyst for a mild, solvent-free Knoevenagel condensation of aldehydes with ethyl cyanoacetate or malononitrile to afford olefins in excellent yields with (E)-geometry. This method, which is even improved by microwave irradiation, is applicable for a wide range of aldehydes.
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Details
The document discusses the use of triphenylphosphane (TPP) as an efficient catalyst for the Knoevenagel condensation of aldehydes with acidic methylene compounds like ethyl cyanoacetate and malononitrile. This method, which operates under mild, solvent-free conditions, yields substituted olefins with high stereoselectivity and excellent yields. The reaction is applicable to a wide range of aldehydes, including aromatic, aliphatic, and heterocyclic substrates. Microwave irradiation is employed to enhance reaction rates and yields. The study highlights that both electron-rich and electron-deficient aldehydes perform well, with electron-deficient aldehydes giving higher yields. Heterocyclic aldehydes also show higher yields compared to aromatic and aliphatic aldehydes. The method avoids the use of environmentally harmful solvents and provides a clean reaction profile without forming Michael adducts. The document concludes that TPP is a novel, mild, and efficient catalyst for the preparation of olefinic compounds via the Knoevenagel reaction, offering advantages such as mild conditions, high conversions, cleaner reactions, and operational simplicity. The study's findings are supported by spectroscopic data and comparisons with authentic samples.
Key Words
Aldehydes, Knoevenagel Condensation, Microwave activation, Phosphanes, Condensation
ID: J24-Y2004-170
