Development of Novel Glycosylation Reaction Using Odorless Benzenethiols

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p-Octyloxybenzenethiol (1) was first synthesized as a new odorless benzenethiol. Using 1, 1-(p-octyloxy)phenyl-thio-glycosides (2) were prepared as a new type of glycosyl donors in the glycosylation reaction. After trying the glycosylation reactions under several conditions, it was found that 2 were excellent glycosyl donors in glycosylation reaction activated with N-iodosuccinimide and triflic acid. All the procedure from the preparation of 2 to the glycosylation reaction could be attained completely under conditions where no malodorous stench was generated.Next, another glycosylation reaction was performed using a combination of 2 and 1-(p-octyloxy)phenyl glycosyl sulfoxides (3), which were prepared by the oxidation of 2, as a glycosyl donor and an acceptor, respectively. Promising results were obtained when p-octyloxylphenyl N-phthalimido-D-thio-glucosaminide derivative was activated with NIS and TfOH for the glycosylation of 3 carrying a free hydroxyl group, especially, at the C-6 position. Successive reduction of the resulting disaccharyl sulfoxides with Ph_3P/CBr_4/CH_3CN provided the corresponding thio-glycosides, which could be used as the glycosyl donors in a following glycosylation reaction to afford trisaccharides in good yield. Using the present method, 4-iodo-phenylalkyl ss-D-N-acetylglucosaminyl-(1-2)-ss-D- mannopyranosyl(1-6)-α-D-glucopyranoside (4), which was designed as a monitoring glycoconjugate for the activity of malignant tumor specific N-acetyl-D-glucosaminyltransferase-V.Finally, it is noteworthy that the glycosylation reaction using a combination of 2 and 3, which was developed in the present study, provided a novel and useful synthetic method of oligosaccharides, i. e., the glycosylation reaction from the non-reducing ends.