Palladium based catalysis is the most used tool to perform the formation of C-C, C-O and C-N. There are many sources of palladium such as PdOAc2, PdCl2 or Pd2dba3. However the related methods do not always allow sufficient conversion.

Palladium precatalysts is an efficient solution to generate in-situ the LnPd(0) needed for the reaction. These precatalysts are generally air and moisture stable.

The first palladacycle precatalyst has been reported by Herman and Beller in 19951. Since then Buchwald laboratories has developed several types of palladium.

The first generation of Buchwald palladium precatalysts are phenethylamine derivatives. In presence of a base the LPd(0) can be generated in-situ.

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The second generation of Buchwald palladium precatalysts are 2-aminobiphenyl derivatives. These precatalysts can be activated at room temperature.

2nd_generation_precatalysts_activation

The third generation of Buchwald palladium precatalysts are methylsulfonate salt of 2-aminobiphenyl derivatives. These precatalysts are compatible with bulky ligands and show longer stability in solution.

3rd_generation_precatalysts_activation

The fourth generation of Buchwald palladium precatalysts are methylsulfonate salt of 2-methylaminobiphenyl derivatives. These precatalysts are compatible with bulky ligands and show longer stability in solution.

4th_generation_precatalysts_activation

 

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1 Herman,W.A.; Beller,M. Angew. Chem. Int. Ed., 1995, 34, 1844-1848.