Studies of N-hydroxy-N'-aminoguanidine derivatives by nitrogen-15 nuclear magnetic resonance spectroscopy and as ribonucleotide reductase inhibitors.

Hydroxyguanidine, with the imino group of guanidine and the hydroxyamino group of hydroxyurea, has functional groups believed to be important for both anticancer and antiviral activities (Adamson, R. H. Nature (London) 1972, 236,400-401). Three new N-hydroxy-N‘mninoguanidine derivatives have been synthesized and found to be 20-30 times more active than the hydroxyguanidine itself as inhibitors of ribonucleotide reductase from rat Novikoff tumors (Tai, W. A.; Lai, M. M.; Lien, E. J. “Novel -Hydroxyguanidine Derivatives as Antiviral Agents”, North American Medicinal Chemistry Symposium, University of Toronto, Toronto, Canada, June 20-24,1982; Abstr, p 144). The character of the tautomeric equilibria, the pK_a values, and the protonation sites of these hydroxyguanidine derivatives have been determined by ^(15)N NMR spectroscopy.