N,N-Dialkylation of Acyl Hydrazides with Alcohols Catalyzed by Amidato Iridium Complexes via Borrowing Hydrogen

Abstract

Direct N,N-dialkylation of acyl hydrazide catalyzed by a series of amidato iridium complexes bearing an electron-donating group in the ligand using methanol or ethanol as the alkyl reagent under weak base conditions (10 mol % KHCO3) is described. A wide range of acyl hydrazide derivatives are converted to the corresponding N,N-dialkylated products in excellent yields (38 examples, yields of ≤96%). On the basis of the control experiments and nuclear magnetic resonance studies, a plausible mechanism was proposed. The experimental results indicate that ortho electron-donating groups on the phenyl moiety of the picolinamide ligand play a crucial role in catalytic activity.