Pd-catalyzed intermolecular amidation of aryl halides: the discovery that xantphos can be trans-chelating in a palladium complex.
A general method for the intermolecular coupling of aryl halides and amides using a Xantphos/Pd catalyst is described. This system displays good functional group compatibility, and the desired C-N bond forming process proceeds in good to excellent yields with 1-4 mol % of the Pd catalyst. Additionally, the arylation of sulfonamides, oxazolidinones, and ureas is reported. The efficiency of these transformations was found to be highly dependent on reaction concentrations and catalyst loadings. A Pd complex resulting from oxidative addition of 4-bromobenzonitrile, (Xantphos)Pd(4-cyanophenyl)(Br) (II), was prepared in one step from Xantphos, Pd(2)(dba)(3), and the aryl bromide. Complex II proved to be an active catalyst for the coupling between 4-bromobenzonitrile and benzamide. X-ray crystallographic analysis of II revealed a rare trans-chelating bisphosphine-Pd(II) structure with a large bite angle of 150.7 degrees.
Yin
Jingjun
J
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Buchwald
Stephen L
SL
D000577:Amides / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D002614:Chelating Agents / Q000737:chemistry; D018360:Crystallography, X-Ray; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D006846:Hydrocarbons, Halogenated / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry; D010165:Palladium / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*
D000577:Amides; D002614:Chelating Agents; D006841:Hydrocarbons, Aromatic; D006846:Hydrocarbons, Halogenated; D009942:Organometallic Compounds; D010720:Phosphines; D010165:Palladium