Synthesis of alkyl-D-fructosides

In fructose alkylation, van der Heiden et al. have shown that MCM-41 was the catalyst of choice. With short alkyl chain alcohols, quantitative conversions were obtained.[49] In the case of alkyl-fmctosides, 5h of reaction time at reflux of the competent alcohol were required. Only the two kinetically favoured fructofurano-sides were formed. With butanol, the reaction took place at a slightly higher temperature and required a longer reaction time, thus allowing the formation of the jS-D-fructopyranoside isomer besides the two fructofuranosides. 

With long alkyl chain alcohols, the conversion of fructose with 1-octanol to octylfructosides was only 60%, but with 1-decanol and 1-dodecanol the conversion dropped to 40% due to competing of fructose ring opening. However, in 1,2-dimethoxyethane as solvent, a yield in dodecyl-D-fructosides of 60% was obtained after 1.5 h at 83 °C. 

Fructose-containing disaccharides, such as leucrose, isomaltulose and lactulose, can also be alkylated over H-MCM-41 without any cleavage of the glycosidic bond between the two sugar units.[50] MCM-41 can be used as catalyst, yields in alkyl leucrosides, isomaltulosides and lactulosides are obtained in 24 h at reflux of short alkyl chain (C2-C4) alcohols with yields of 80-99%. 

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