Enzymatic route to alkyl glycosides having oligomeric head groups

Cyclodextrin glycosyl transferase (CGTase) from Bacillus macerans was used to catalyse the coupling of alpha-cyclodextrin to alkyl beta-glycosides. The acceptor substrate dodecyl beta-maltoside was thus converted to dodecyl beta-D-maltooctaoside. Further coupling steps and disproportionation reactions occurred, but by optimisation of the reaction time, a yield of 50% of the primary coupling product was obtained. The method worked well for a range of acceptors with different length of the carbohydrate part (1-3 glucose residues) and the hydrocarbon chain (10-14 carbon atoms). With respect to the principles of green chemistry, the method is superior to previously used methods involving protection/deprotection reactions.