I need prepare a series of 2-amino-pyridines around 2003, and found this paper by SciFinder.
I tested the reaction of 1-Boc-piperidine and 2-chloro-3-methyl- pyridine in 50mg scale using 5 mmol% catalysts.
The reactions were not completed in 3h at rt. When the mixture was shaken at 50 °C for 2h, the reaction was completed. The separated yield is 80%.
The amine and 2-chloro-3-methyl-spyridines are more hindered than morpholine and 2-chloropyridine exemplified in the paper (Table 1, example 12).
I scaled up the reaction in 0.6g scale and prepared several different 2-aminopyridines, all of the reactions went completed in 5h at 50 °C, and the average yields are 65 ~ 90%.
For each reaction, I tested it in small scale first, then, scaled up. The catalyst-system is reproducible.
The saturated carbene ligand is easy to handle in small amount (white solid, stable under air, compared to Pd(PPh3)4) .
In conclusion, I am very happy with this catalyst-system.