52970-46-4Relevant academic research and scientific papers
Intramolecular C-N bond formation in the reductive elimination of ortho-palladated arylhydrazones of acetophenone
Carbayo, Aránzazu,Cuevas, José V.,García-Herbosa, Gabriel
, p. 15 - 20 (2002)
Carbonylation in dichloromethane at room temperature of the dimeric ortho-palladated complex [Pd{C6H4C(CH3)=N- NHC6H5} (μ-Cl)]2 yields in a first step the monocarbonyl isoindolin-1-one. Addition of the stoichiometric amount of NaOMe to the monocarbonyl complex [Pd{C6H 4C(CH3)=N- NHC6H5}Cl(CO)] in solution leads instantaneously to reductive elimination and affords the indazole derivative, 3-methyl-l- phenyl-indazole, in high yield. Carbonylation of the related complex [Pd{C6H4C(CH3)=N-NHC6 H4-p-NO2}(μ-Cl)]2 yields in solution the monocarbonyl [Pd{C6H4C(CH3)=N-NHC6H 4p-NO2}Cl(CO)] which in minutes affords high yield of the isoindolinone derivative, 2-(4-nitroanilino)-3-methylene-isoindolin-1-one. Such different behaviour sheds light on the mechanistic grounds that govern the intramolecular C-N bond formation and the cyclization of ortho-palladated acetophenonearylhydrazones, and shows that the acidity of the N-H bond controls the rate of the reactions. The requirement of the formation of a palladium-nitrogen amido bond cis to a palladium-carbon bond is supported for these results. We suggest that a tautomeric equilibrium of the hydrazonato ligand accounts for the two alternate pathways.
