Dimethyl Sulfide → 7-Bromo-1-(2-chloro-3,6-difluorobenzyl)-1,2,3,4-tetrahydropyrazino[2,3-b]pyrazine

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Reaction Steps

To a solution of 7-bromo-1-(2-chloro-3,6-difluorobenzyl)-1,4-dihydropyrazino[2,3-b]pyrazine-2,3-dione (2.5 mmol, 1.0 g) in THF (5 mL) was added BH3.Me2S (7.5 mmol, 3.75 mL, 2.0 M in THF). The resulting solution was refluxed for 2 hrs under N2. Excessive BH3 was quenched by addition of MeOH at rt then heating the reaction mixture for 10 min. After volatile components were removed on rotavap, the residue was subjected to a silica gel column chromatography by using 4:1 ratio of CH2Cl2/MeOH (pre-saturated with ammonia gas) as eluents, furnishing 7-bromo-1-(2-chloro-3,6-difluorobenzyl)-1,2,3,4-tetrahydropyrazino[2,3-b]pyrazine in 20% yield (0.19 g).

Provenance & Evidence