Glycosyl cyanation reactions

As has already been pointed out, the Finkelstein reaction can be conducted in situ in the absence of solvents. For example, alkylations of purine and pyrimidine bases with alkyl halides and dimethyl sulfate have been carried out by solid/liquid phase-transfer catalysis in the absence of any additional solvent [48], as have cyanation of haloalkanes [49] and / -eliminations [50]. Noteworthy is the synthesis of glycosyl isothiocyanates by the reaction of potassium thiocyanate with molten glycosyl bromide at 190 °C [51]. 

Glycosyl fluorides, already addressed as substrates for cyanations and allylations, are excellent substrates for radical-mediated C-glycosidations. As shown in Scheme 7.80, Nicolaou et al. [43] demonstrated such reactions in the coupling of 2,3,4,6-tetra-O-benzyl-D-glucopyranosyl fluoride with acrylonitrile. The reaction gave a 61% yield with an anomeric ratio of greater than 10 1 favoring the a isomer. 

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