Ammonia → 7-Bromobenzothiazole-2,5-diamine

Participants

Reaction Steps

To a stirred mixture of EtOH (8.37 L) and water (8.37 L) at rt was added (2-bromo-4,6-dinitro-phenyl)thiocyanate (549 g, 1.81 mol) followed by addition of Fe powder (2.02 kg, 36.11 mol) and drop wise addition of HCl (12N, 527 mL) over 30 min. The resulting reaction mixture was stirred at rt for 20 min then heated to 80° C. for 45 min. After completion of the reaction (by TLC) the reaction mixture was cooled to rt and basified to pH 8-10 by addition of aqueous ammonia solution. The resulting solution was passed through celite bed, washed with EtOAc and the combined filtrate evaporated under reduced pressure. To the resulting residue was added water (8 L) then extracted with EtOAc (2×4 L). The combined organics were washed with brine, dried (anhydrous Na2SO4), filtered and concentrated under reduced pressure to obtain the desired product (412 g, 93%). 1H NMR (DMSO-d6): δ 5.16 (br s, 2H), 6.50 (d, J=2.0 Hz, 1H), 6.53 (d, J=1.60 Hz, 1H) and 7.44 (br s, 2H). LCMS: 243.86 [M+H]+.

Provenance & Evidence