title: Pd-carbene catalyzed carbonylation reactions of aryl iodides.
abstract: A series of carbene complexes [PdBr(2)((i)Pr(2)-bimy)L] (C2-C13) with different types of co-ligands (L) have been tested for their catalytic activities in the carbonylative annulation of 2-iodophenol with phenylacetylene in DMF to afford the respective flavone 2a. Complex C12 with an N-phenylimidazole co-ligand showed the best activity and also afforded high yields when the substrate scope was extended to other aryl or pyridyl acetylenes. In addition, catalyst C12 was also efficient in the carbonylative annulation of 2-iodoaniline with acid chlorides giving the desirable 2-substituted 4H-3,1-benzoxazin-4-ones (4) in good yields. Additionally, this Pd-NHC complex also proved to be a very efficient catalyst for the hydroxycarbonylation of iodobenzene derivatives at low catalyst loading and under low CO pressure. These results demonstrate the versatility and efficiency of this phosphine-free Pd(II)-NHC complex in different types of carbonylations of aryl iodides under mild conditions.
authors.affiliation: State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.
authors.forename: Liqin
authors.initials: L
authors.lastname: Xue
authors.forename: Lijun
authors.initials: L
authors.lastname: Shi
authors.forename: Yuan
authors.initials: Y
authors.lastname: Han
authors.forename: Chungu
authors.initials: C
authors.lastname: Xia
authors.forename: Han Vinh
authors.initials: HV
authors.lastname: Huynh
authors.forename: Fuwei
authors.initials: F
authors.lastname: Li