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