The synthesis of oligoether-substituted benzimidazolium bromides and their use as ligand precursors for the Pd-catalyzed Heck coupling in water
作者:Süleyman Gülcemal、Sema Kahraman、Jean-Claude Daran、Engin Çetinkaya、Bekir Çetinkaya
DOI:10.1016/j.jorganchem.2009.07.010
日期:2009.10
preformed Pd(II) complexes 14, 15, 18 and 19 were tested as catalyst for the Heck coupling reaction in water. The influence of the oligoether and benzyl substituents on N atoms and CH3-substituents on the 5,6-positions of benzimidazole frame were investigated under the same conditions in the Heck coupling reaction. In situ formed catalysts showed better conversions than the isolated Pd(II) complexes.
寡醚取代的(CH 3(OCH 2 CH 2)n –;n = 1、2或3)苯并咪唑鎓溴化物(3 – 7)和寡醚连接的(–CH 2(CH 2 OCH 2)n CH 2 –,ñ = 1,2或3)bisbenzimidazolium二溴化物(8 - 13)的N-取代的苯并咪唑的quarternization(制备1和2)与体积庞大的苄基溴(ARCH 2 BR:氩= C 6 H ^ 2(CH 3)3 -2,4,6和C 6(CH 3)5)。通过在室温下在二氯甲烷中使用Ag配合物作为卡宾转移剂,合成了衍生自4和6的反式双(卡宾)钯(II)配合物14和15。此外,4和6与Pd(OAc)2和NaBr的反应产生了Pd(II)二聚体16和17,它们很容易被三苯基膦裂解,得到苯环化的单卡宾(NHC)单膦Pd(II)络合物[PdBr 2(NHC)(PPh3)](18和19)。通过使用元素分析,1 H,13 C和31