Synlett 2004(12): 2188-2190  
DOI: 10.1055/s-2004-831309
LETTER
© Georg Thieme Verlag Stuttgart · New York

Sustainable Transesterification of β-Ketoesters Catalyzed by Amine Grafted on Silica Gel

Hisahiro Hagiwara*a, Aiko Kosekib, Kohei Isobea, Ken-ichi Shimizub, Takashi Hoshib, Toshio Suzukib
a Graduate School of Science and Technology, Niigata University, 8050, 2-Nocho, Ikarashi, Niigata 950-2181, Japan
b Faculty of Engineering, Niigata University, 8050, 2-Nocho, Ikarashi, Niigata 950-2181, Japan
Fax: +81(25)2627368; e-Mail: hagiwara@gs.niigata-u.ac.jp;
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Publikationsverlauf

Received 7 June 2004
Publikationsdatum:
26. August 2004 (online)

Abstract

Transesterification of β-ketoesters with various alcohols has been effected by N,N-diethylaminopropylated silica gel (NDEAP) as a catalyst in refluxing xylene. Generality of the reaction was demonstrated by successful transesterification of olefinic alcohols, tertiary alcohols and alcohols having acid- or base-sensitive substituents. The catalyst has been efficiently recycled more than five times without any re-activation.

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NDEAP was prepared according to the same procedure as ref.5b, using N,N-diethyl-3-aminopropyl(trimethoxy)silane and silica gel. Nitrogen loading was 0.72 mmol/g according to combustion analysis.

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Typical Experimental Procedure: To a stirred solution of menthol (2a, 156 mg, 1 mmol) and methyl acetoacetate (1a, 130 µL, 1.2 mmol) in anhyd xylene (4 mL) was added NDEAP pellets (279 mg, 0.72 mmol/g, 0.2 mmol) and the resulting mixture was heated at reflux for 7 h. After removal of the catalyst by filtration, the filtrate was evaporated to dryness to give a residue, which was purified by column chromatography on silica gel to give β-ketoester 3a (238 mg, 99%). The catalyst NDEAP was re-used intact for the subsequent reaction.