State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 73000, China.
Dalton Trans. 2011 Aug 7;40(29):7632-8. doi: 10.1039/c1dt10433k. Epub 2011 Jun 15.
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.
一系列带有不同类型辅助配体 (L) 的卡宾配合物 [PdBr2((iPr2-bimy)L)] (C2-C13) 已被测试用于在 DMF 中 2-碘苯酚与苯乙炔的羰基化环化反应中催化生成相应的黄酮 2a。带有 N-苯基咪唑辅助配体的配合物 C12 表现出最佳的活性，当底物范围扩展到其他芳基或吡啶基乙炔时，也能获得高产率。此外，催化剂 C12 也能有效地催化 2-碘苯胺与酰氯的羰基化环化反应，以良好的产率得到所需的 2-取代 4H-3,1-苯并恶嗪-4-酮 (4)。此外，该 Pd-NHC 配合物在低催化剂负载和低 CO 压力下，也被证明是碘苯衍生物羟基羰基化反应的非常有效的催化剂。这些结果表明，在温和条件下，该无膦 Pd(II)-NHC 配合物在不同类型的芳基碘的羰基化反应中具有多功能性和高效性。
