Synthesis of bulky and electron-rich MOP-type ligands and their applications in palladium-catalyzed C-N bond formation

J Org Chem. 2006 Aug 18;71(17):6522-9. doi: 10.1021/jo060945k.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amination
  • Amines / chemistry
  • Carbon / chemistry*
  • Catalysis
  • Electrons*
  • Halogens / chemistry
  • Ligands
  • Molecular Structure
  • Nitrogen / chemistry*
  • Nitrosamines / chemistry*
  • Palladium / chemistry*

Substances

  • Amines
  • Halogens
  • Ligands
  • Nitrosamines
  • methyl-2-oxopropylnitrosamine
  • Palladium
  • Carbon
  • Nitrogen