TAUTOMERISM OF SACCHARIDE HYDRAZONES IN SOLUTION AND THEIR REACTION WITH NITROUS ACID

Article abstract of DOI:10.1016/0008-6215(83)88077-X

N.m.r. spectroscopy (13C and 1H) has been used to show that saccharide hydrazones in solution in hydrazine exist mainly as the syn acyclic-tautomer.In deoterium oxide solutions, slow tautomerisation occours to give glycosylhydrazines; at pH 6 tautomerism is rapid and the latter preponderate; exceptions are the hydrazones of D-ribose and L-arabinose which give almost equal proportions of acyclic and cyclic tautomers at pH 6.Reaction of representative saccharide hidrazones with nitrous acid gives a mixture of the corresponding saccharide and the β-glycosyl azide, the latter being formed from the glycosylhydrazine tautomer.