Preparation, Properties, and Reductive Alkylation of Arylhydrazides

1-Acyl-2-arylhydrazines (1), readily obtained in high yield from the condensation of arylhydrazines and the appropriate liquid carboxylic acid (2). underwent reductive alkylation with the same or different liquid carboxylic acids (2) and NaBH4 to give 1-acyl-2-alkyl-2-arylhydrazines (3) in good to moderate yields. The carbaxylic acid has both the role of supplying the entering alkyl group and of acting as solvent. Most likely, it also modifies the BH4- anion to an active reducing agent under those conditions. The H-1 NMR criteria for identifying the location of acylation of hydrazines and E and Z isomers are given. The MS spectra of the prepared hydrazides were analyzed in order to identify relevant structural features leading to specific fragmentations.