4,7-Dibromo-2,1,3-benzothiadiazole → 3,6-Dibromobenzene-1,2-diamine

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

NaBH4 (26 g, 680 mmol, 10 equiv) was added portionwise (2 h) to a vigorously stirred suspension of 4,7-dibromo-benzo[1,2,5]thiadiazole (Step 1.7) (20 g, 68.0 mmol) in EtOH (400 mL), under a nitrogen atmosphere and keeping the internal temperature below 15° C. The reaction mixture was allowed to warm to 30° C., stirred for 1 h, cooled to 5° C., quenched by addition of H2O (50 mL), and concentrated. The residue was diluted with Et2O/H2O. The resulting suspension was filtered and the filtrate extracted with Et2O. The organic phase was washed with H2O and brine, dried (Na2SO4), filtered and concentrated. The residue was triturated in hexane to provide 12 g of the title compound as a white solid: ESI-MS: 262.9/264.9/266.9 [M−H]−; tR=4.20 min (System 1).

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