A series of air-stable [(Np3P)Pd(Ar)Br]2 (Np = neopentyl) and (Np3P)Pd(Ar)(amine)Br complexes (amine = morpholine and isobutylamine) have been prepared and tested as precatalysts for the coupling of sterically demanding aryl bromides and aniline derivatives. The complexes are more active than the catalyst generated in situ from Pd2(dba)3 and PNp3. Increasing steric demand of the aryl group on palladium
制备了一系列空气稳定的[(Np 3 P)Pd(Ar)Br] 2(Np =新戊基)和(Np 3 P)Pd(Ar)(胺)Br配合物(胺=吗啉和
异丁胺),并且经测试可作为位阻芳基
溴化物和
苯胺衍
生物偶联的前催化剂。该络合物比由Pd 2(dba)3和
PNp 3原位产生的催化剂更具活性。
钯上芳基空间需求的增加与催化剂活性的提高有关。[(Np 3 P)Pd(2,6-Me 2 C 6 H 3)Br] 2催化的反应与使用Pd 2(dba)3 /
PNp 3的那些相比,在更低的温度下以更高的收率有效地发生。与[(Np 3 P)Pd(Ar)Br] 2络合物相比,胺加合物的反应速率和转化率更低。胺加合物的较低活性似乎是由缓慢的碱促进的还原消除产生的,从而产生催化活性的LPd(0)物质。