Synthesis of Alkyl Fructosides Using Solid Acid Catalysts. Part I: Silica-Alumina Cracking Catalysts
摘要:
Silica-alumina cracking catalysts and acid clays efficiently catalyze the 2-O-alkylation of D-fructose with long chain alcohols. Under the conditions applied virtually no degradation of fructose is observed. L-Sorbose and the aldopentoses also undergo silica-alumina-catalyzed alkylation. The rate of conversion is related to the solubility of the monosaccharide and the stability of the intermediate oxocarbenium ion. Best results in fructose alkylation are obtained by applying a recirculation method with butyl fructoside as soluble intermediate.
O-unprotected aldoses (D-glucose, D-galactose and D-mannose) and D-fructose in THF or 1,4-dioxane using anhydrous FeCl3 as promoter afforded either aldofuranosides 1, 3, 4 in good overall yields or exclusively β-D-fructopyranosides 7. Conversely α-D-aldopyranosides 2, 5 and 6 were obtained respectively from D-glucose, D-mannose and N-acetyl-D-glucosamine when the reactions were performed in the presence
Mcm-41 Materials as Catalysts for the Synthesis of Alkyl Fructosides
作者:A.M. van der Heijden、F. van Rantwijk、H. van Bekkum
DOI:10.1080/07328309908543987
日期:1999.1.1
derivatives of fructose has lagged because no efficient synthesis was available. We have found that mesoporousmaterials of the MCM-41 type are active and selective catalysts for the alkylation of fructose. Quantitative yields were obtained in the reaction of fructose with lower alcohols, up to C4. For long chain alcohols yields were moderate but the alkyl fructopyranosides could be easily purified. The other
was readily prepared compared to a cage‐shaped analogue. This host associated with lipophilic glycosides to form chiral complexes, and the association constants were sufficiently high as to be comparable to those of the cage‐shaped analogue. Furthermore, this host extracted native monosaccharides into a lipophilicsolvent.