Hydrochloric Acid → Pyrazine, 2-phenyl-

Participants

Reaction Steps

Chloropyrazine (20.68 gram, 177 mmol) and [1,2-bis(diphenylphosphino)ethane]nickel(II) chloride (41.08 gram, 77.8 mmol) in dry THF (1.5 liter) were mixed and stirred for 80 minutes in a flask (cooled with a water bath) under nitrogen. A solution of phenylmagnesium bromide (3M in Et2O) (103 ml, 309 mmol) was added slowly through a dropping funnel into the cooled brick-red slurry at room temperature under nitrogen over 3.5 hours. After stirring at room temperature overnight, TLC showed that the reaction was complete. 3 N HCl (100 ml) was added slowly through a dropping funnel under nitrogen and the mixture was stirred for one hour. The THF layer was separated from the aqueous layer. The aqueous layer was adjusted to pH 12 with 6 N NaOH and extracted with EtOAc (100 ml, 3×). The organic fractions (THF and EtOAc) were combined and dried over MgSO4, filtered and concentrated to give a solid. The product was purified by flash chromatography on 300 g of flash grade silica gel in 2.5% EtOAc/CH2Cl2 to give 10.79 gram (69 mmol, 39%) of 2-phenylpyrazine, m.p. 69-70° C.; FAB mass [M+1]+ 157;

Provenance & Evidence