title: Knoevenagel reaction in water catalyzed by amine supported on silica gel.
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.
authors.affiliation: Graduate School of Science and Technology, Niigata University, 8050, 2-Nocho, Ikarashi, 950-2181, Niigata, Japan.
authors.forename: Kohei
authors.initials: K
authors.lastname: Isobe
authors.forename: Takashi
authors.initials: T
authors.lastname: Hoshi
authors.forename: Toshio
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hisahiro
authors.initials: H
authors.lastname: Hagiwara
mesh_terms: D000085:Acetates / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry; D000588:Amines / Q000737:chemistry*; D002384:Catalysis; D004952:Esters; D058428:Silica Gel; D012822:Silicon Dioxide / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000085:Acetates; D000447:Aldehydes; D000588:Amines; D004952:Esters; D014867:Water; D058428:Silica Gel; D012822:Silicon Dioxide; C007659:ethyl cyanoacetate