Selective C-arylation of free (NH)-heteroarenes via catalytic C-H bond functionalization.
A new system for palladium-catalyzed arylation of a broad spectrum of free (NH)-heteroarenes has been developed (indole, pyrrole, pyrazole, 2-phenylimidazole, imidazole, benzimidazole, and purine). Remarkable selectivity has been achieved in the presence of MgO base, providing single C-arylation products, while no N-arylation and no bis-arylation products have been detected. In the case of free imidazole, exclusive C-4 arylation may be switched to exclusive 2-arylation by the addition of CuI to the Pd/Ph3P/MgO system. When free aryl-(NH)-azoles are desired, direct arylation eliminates three steps in comparison to standard methods, including N-protection, stoichiometric metalation or halogenation, and N-deprotection.
Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
Bengü
B
Sezen
Dalibor
D
Sames
D001393:Azoles / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D006841:Hydrocarbons, Aromatic / Q000138:chemical synthesis / Q000737:chemistry*; D008277:Magnesium Oxide / Q000737:chemistry; D010165:Palladium / Q000737:chemistry
D001393:Azoles; D006841:Hydrocarbons, Aromatic; D008277:Magnesium Oxide; D010165:Palladium