Improved and large-scale synthesis of certain glycosyl cyanides. Synthesis of 2,5-anhydro-5-thio- d-allononitrile

The first synthesis of 2,5-anhydro-5-thio- d-allononitrile starting with l-lyxose, via a trifluoromethanesulfonic ester intermediate, has been accomplished. Methods have been developed to achieve a large-scale synthesis of 3,4,5,7-tetra- O-acetyl-2,6-anhydro- d- glycero- d- talo-heptononitrile ( 5). An improved procedure has been developed to synthesize 2,5-anhydro-3,4,6-tri- O-benzoyl- d-gulononitrile ( 9). The structures of 5 and the thioamide derivative from 9, 2,5-anhydro-3,4,6-tri- O-benzoyl- d-gulonothioamide, were confirmed by X-ray crystallographic analysis.