3,4-Dimethoxyaniline → 6-bromo-N-(3,4,5-trimethoxyphenyl)imidazo[1,2-a]pyrazin-8-amine

Participants

Reaction Conditions

Reaction Steps

Preparation of 6-bromo-N-(3,4-dimethoxyphenyl)imidazo[1,2-a]pyrazin-8-amine (2) A mixture of 3,4-dimethoxyaniline (18.0 g, 118 mmol), 6,8-dibromoimidazo[1,2-a]pyrazine (25.0 g, 90.4 mmol), and N,N-diisopropylethylamine (11.7 g, 90.4 mmol) in DMF (500 mL) was stirred at 120° C. overnight. After this time, the reaction was cooled to room temperature and concentrated to approximately 100 mL under reduced pressure. The dark brown reaction mixture was poured into ice-cold water (300 mL) and stirred for 10 min. The resulting brown precipitate was filtered and the filter cake washed with water (100 mL). The filter cake was dried under vacuum and recrystallization from methanol (˜800 mL) to afford 6-bromo-N-(3,4,5-trimethoxyphenyl)imidazo[1,2-a]pyrazin-8-amine (2) (23.3 g, 74%) as a light brown needle-shaped solid: 1H NMR (300 MHz, DMSO-d6) 9.81 (s, 1H), 8.22 (s, 1H), 7.93 (s, 1H), 7.75 (d, J=2.4 Hz, 1H), 7.62 (s, 1H), 7.53 (dd, J=8.7, 2.4, 1H), 6.94 (d, J=8.7 Hz, 1H), 3.77 (s, 3H), 3.75 (s, 3H); ESI MS m/z 349.2 [M+H]+; HPLC, 6.92 min, >99% (AUC).

Provenance & Evidence