Gluco-triflate

The preparation of a(1 3) and (l->3)-thiodisaccharides in the gluco and xylo series was readily achieved in high yield by Sn2 displacement of a triflate... 

Boron trifluoride diethyl etherate Sodium bicarbonate Palladium on charcoal Sodium periodate Hydroperoxide, 1,1-dimethylethyl Titanium tetraisopropoxide Ethyl diisopropylamine Triethylamine Ammonium sulfate Trimethylsilyl triflate d-3-oxo-a-D-gluco-pyranoside -oxo-a-D-erythro-hexopyranoside... 

Depending on their location on a sugar, sulfonates have very different reactivities. This is apparent, for example, in the behaviour of tosylates. The tosylate of the primary alcohol function can be substituted without difficulty, even in solvents which are not polar or aprotic. Substitution at positions 3 and 4 are only possible in DMF solution. Substitution at position 2 is absolutely impossible. On the other hand, it is often observed without problems at position 2 starting from a triflate or an imidazylate. These reactivity differences clearly appear in the triple substitution reaction of the tris-triflate P-D-galacto 7 J by benzoate (Alais and David 1990). The latter is prepared from the triol in 5 h at 0 C. It reacts quantitatively with tetrabutylammonium benzoate in toluene in 45 min at room temperature to give the D-gluco substitution product at C-4 and C-6. Heating for 1 h at 100 C then leads to the D-manno tribenzoate 74. 

The N -allyloxy-carbonyl derivative of 2-methyl-(l,2-dideoxy-a-D-gluco-pyrano)[2,l-d]-l-imidazolines, inhibitors of /1-N-acetylglucosaminidases, have been formed as a byproduct during a study on tetra-O-acetyl-2-allyloxy-2-carbonylamino-)S-D-glucose synthesized as a glycosyl donor and when no available acceptor was present in the reaction media of acetonitril in the presence of trimethysilyl triflate it formed almost quantitatively [78,79). 

In closely related studies Mukaiyama has used the (trichloromethyloxycarbonyl)amino group, and with the analogous p-tetra-acetate and silylated alcohols in the presence of tin triflate has made p-glycosides in the gluco- and the galacto- series. When they used O-... 

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