Pd(II)-catalyzed aromatic coupling of oxabenzonorbornadienes with triarylphosphines. (Image by JIANG Gaoxi et al.) 

Phosphine compounds are widely used in transitional metal catalyzed reaction as ligands. They act as catalysts in various catalytic reactions as well. However, the exploitation of tertiary phosphine itself in the direct activation of the C-P bond remains unexplored yet. This may be due to its intrinsic characteristics, namely high C-P bond energy of around 513 kJ/mol and strong interaction to metal catalysts. Furthermore, it is easily oxidized to Ar₃P=O.  

The research group headed by Professor JIANG Gaoxi at the Lanzhou Institute of Chemical Physics (LICP) of the Chinese Academy of Sciences (CAS) has developed the first example of a Pd(II)-catalyzed aromatic coupling of oxabenzonorbornadienes with triarylphosphines in the absence of any additional activators under neutral reaction conditions.  

In this reaction, triarylphosphines function as both ligands and aryl donors. The catalytic process underwent stable C-P bond cleavage and tolerated diverse functional groups. The preliminary mechanistic study reveals that the β-O-elimination of oxobridged dienes plays the key role for such a catalytic cycle. 

The process has provided a catalytic method for the activation of a stable C-P bond and opened a new window for the application of phosphines. 

The findings has been published in Organic Letters(Organic Letters, 2015,17, pp 4628-4631) .  

The work has received financial support from the State Key Laboratory for Oxo Synthesis and Selective Oxidation of the LICP.  

Contact: 

JIANG Gaoxi 

State Key Laboratory for Oxo Synthesis & Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China 

E-mail: gxjiang2012@sinano.ac.cn