Amidrazones 9. Convenient Syntheses of 1-Alkyl-1-Phenylhydrazines and α,β-Unsaturated Amidrazones Via Base-Promoted Reactions of 1,1-Disubstituted-3-Amino-4,5-Dihydro-1H-Pyrazolium Salts

Abstract A simple, efficient procedure for the conversion of phenylhydrazine to 1-alkyl-1-phenylhydrazines via base-promoted hydrolysis of 1-alkyl-3-amino-4,5-dihydro-1-phenyl-1H-pyrazolium iodides (2) is described. N1, N1-disubstituted hydrazones of trans-cinnamamide and acrylamide are obtained by Hofmann-type ring openings of 1,1 -disubstituted-3-amino-4,5-dihydro-5-phenyl (or 5-unsubstituted) -1H-pyrazolium halides (5, 7).