Synthesis of bulky and electron-rich MOP-type ligands and their applications in palladium-catalyzed C-N bond formation.
A series of 2-dialkylphosphino-2'-alkoxy-1,1'-binaphthyl ligands (6a-c and 8a-c) have been prepared conveniently by a lithium-initiated ring-opening reaction of dinaphthofuran, followed by selective phosphorylation. These compounds displayed a remarkable air and moisture stability, both in solid form and in solution. Application of these phosphine ligands in palladium-catalyzed C-N bond forming reactions revealed the crucial roles of the steric bulk of the substituents on the phosphorus atom governing the catalytic activity. Specifically, 2-di-tert-butylphosphino-2'-isopropoxy-1,1'-binaphthyl (8b) proved to be the most effective for the aminations of aryl halides with primary amines, while the less bulky 2-dicyclohexyl-2'-methoxy-1,1'-binaphthyl (6a) was more effective for the aminations with secondary amines. The steric and electronic effects of the ligands were analyzed to account for these observations.
Xie
Xiaomin
X
School of Chemistry and Chemical Engineering, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240, China.
Zhang
Tony Y
TY
Zhang
Zhaoguo
Z
D000586:Amination; D000588:Amines / Q000737:chemistry; D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D004583:Electrons; D006219:Halogens / Q000737:chemistry; D008024:Ligands; D015394:Molecular Structure; D009584:Nitrogen / Q000737:chemistry*; D009602:Nitrosamines / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*
D000588:Amines; D006219:Halogens; D008024:Ligands; D009602:Nitrosamines; C413927:methyl-2-oxopropylnitrosamine; D010165:Palladium; D002244:Carbon; D009584:Nitrogen