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Imine Metathesis by Silica-Supported Catalysts Using the Methodology of Surface Organometallic Chemistry
Published on: October 18, 2019
Knoevenagel reaction in water catalyzed by amine supported on silica gel
Kohei Isobe1, Takashi Hoshi, Toshio Suzuki
1Graduate School of Science and Technology, Niigata University, 8050, 2-Nocho, Ikarashi, 950-2181, Niigata, Japan.
Abstract:
An environmentally benign and sustainable Knoevenagel reaction of aldehyde with ethyl cyanoacetate has been achieved at ambient temperature in water employing 3-aminopropylated silica gel (NAP) as a catalyst. Wide applicability of the reaction is illustrated by the results that not only arylaldehydes of both electronic characters but also aliphatic aldehydes afforded the products. The reaction condition was so mild that aldehydes having acid- or base-sensitive substituents provided substituted alpha-cyano-alpha, beta-unsaturated esters. The catalyst has been efficiently recycled more than five times without any pre-treatment. Catalyst loading was successfully reduced to 0.0029 mmol% (TON = up to 9,226). This protocol was also applicable to the Knoevenagel reaction of malononitrile in good yields in water.
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