Glucopyranosyl Isocyanates as Versatile Glycosylating Reagents for the Preparation of Neoglycoconjugates

Abstract

A new and simple synthetic method for the preparation of glucopyranosyl isocyanates has been developed. This method establishes a convenient access to the urea- and carbamate-tethered neoglycoconjugates starting from glucopyranosyl isocyanates.

Key words

glycosylation - glycosides - carbohydrates - synthesis

References

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8

Since glucopyranosyl isocyanate cannot be detected by silica-gel TLC analysis, two equivalents of amine were employed for the transformation to the corresponding urea.

9

In the case of β-carbamate 9 (Scheme [3] ), similar stereospecificity was also observed in the elimination reaction.

11

The corresponding β-isomers of 16 and 17 were also prepared using a similar procedure to Scheme [6] in 88 and 82% yields respectively.

13

Although our previous method using glucopyranosyl isonitriles [5] gives slightly better yields of glucopyranosyl ureas than the present procedure, employing phenyl glucopyranosyl carbamates, we can prepare 9 and 11 from glucopyranosyl azides 4 and 1 in two steps with commercially available reagents. In addition, α-carbamate 11 is easily purified by recrystallization.