Diisobutylaluminum hydride → 5-Bromo-3-(4-hydroxymethyl-phenylamino)-1-methyl-1H-pyrazin-2-one

Participants

Reaction Steps

A slurry of 4-(6-bromo-4-methyl-3-oxo-3,4-dihydro-pyrazin-2-ylamino)-benzoic acid ethyl ester (1) (7.75 g; 22.02 mmol) in CH2Cl2 (200 mL) was cooled to −78° C. under N2. A solution of DIBAL-H (100 mL; 1.0 M in CH2Cl2) was added dropwise over 30 min. to the stirring slurry, and the reaction allowed to warm gradually to rt over 30 min. The reaction stirred for 1 hr at rt, and was monitored by LC-MS until only product was observed. The reaction was cooled to 0° C. in an ice bath and was quenched by slow addition of 1.0 N NaOH (75 mL). The reaction bilayer was extracted with EtOAc (5×100 mL) and the EtOAc layers were pooled, washed with brine and dried over solid Na2SO4. After filtering off the solids, the filtrate was evaporated down to an orange-red oil, which was then redissolved in 3 mL CH2Cl2 and triturated slowly with diethyl ether (20 mL) to provide 5-bromo-3-(4-hydroxymethyl-phenylamino)-1-methyl-1H-pyrazin-2-one (2) as a light orange solid (3.1 g). MS 311.25 & 313.20 (M+H)

Provenance & Evidence