Sodium Carbonate → 3-bromo-5-((1S,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)pyrazin-2-amine

Participants

Reaction Conditions

Reaction Steps

A solution of 5-((1S,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)pyrazin-2-amine (620.0 g, 1904.8 mmol) in DMSO (5 L) and water (400 mL) was cooled to ˜4° C. NBS (389.8 g, 2190.5 mmol) was added in 10 portions within 1 hour and the reaction temperature was controlled under 5° C. with continuous stirring for 30 minutes. After addition of 0.3 M aqueous Na2CO3 (8.5 kg), the reaction temperature was increased to 35° C. MTBE (4.5 kg) was added and the mixture was stirred for a further 10 minutes. After phase separation, the aqueous layer was extracted with MTBE (4 kg). The combined organic layers were washed successively with 0.3 M aqueous Na2CO3 (8.5 kg) and water (8 kg), and concentrated under vacuum at 30-40° C. to give crude product 3-bromo-5-((1S,3S,4S)-4-((tert-butyldimethylsilyl)oxy)-3-fluorocyclohexyl)pyrazin-2-amine as a foam (770 g). This crude product was used in next step without further purification. ESI-MS (m/z): 404.1105, 406.1093 ([M+H]+, 100). HPLC (method A), retention time=14.38 min. 1H NMR (400 MHz, CDCl3): 7.81 (s, 1H), 4.99 (br. s, 2H), 4.37-4.42, 4.25-4.30 (m, 1H), 3.66-3.72 (m, 1H), 2.67-2.73 (m, 1H), 2.26-2.29 (m, 1H), 1.97-2.02 (m, 1H), 1.74-1.87 (m, 2H), 1.44-1.63 (m, 2H), 0.91 (s, 9H), 0.10 (d, J=8 Hz, 6H).

Provenance & Evidence