Synthesis of <i>N,N</i>-Dialkyl-<i>N</i><i>‘</i>-arylhydrazines via Palladium-Catalyzed N-Arylation by Using <i>N,N</i>-Dialkylhydrazines/2LiCl Adducts
[GRAPHICS]The reaction of N,N-dialkylhydrazine/2LiCl adducts with aryl bromides in the presence of Pd-2(dba)(3) as the palladium source, Xantphos or X-phos as the ligands, toluene as the solvent, and NaOBu-t as the base provides an efficient route to N,N-dialkyl-N,-arylhydrazines. Best results were obtained by using N,N-dialkylhydrazine/2LiCl adducts prepared in situ, omitting their isolation.
Palladium-CatalyzedN-Arylation ofN,N-Dialkylhydrazines with Aryl Chlorides
N,N-Dialkyl-N′-arylhydrazines have been prepared usually in high to excellent yields via the reaction of N,N-dialkylhydrazines with arylchlorides in the presence of Pd2(dba)3, Xphos and NaO-t-Bu in dioxane at 120 °C. With ortho-substituted arylchlorides best results have been obtained by using 2-(2′,6′-dimethoxybiphenyl)dicyclohexylphosphine (ligand d) as the ligand.