Methyl 6-Bromo-2-methyl-3-nitrobenzoate synthesis

Yield:731810-03-0 81%

Reaction Conditions:

Stage #1: 6-amino-2-methyl-3-nitro-benzoic acid methyl esterwith hydrogen bromide;acetic acid;sodium nitrite in water at 0; for 0.5 h;
Stage #2: with copper(I) bromide in water at 35 - 80; for 1.5 h;

Steps:

1.2 Step 2. Preparation of 6-Bromo-2-methyl-3-nitro-benzoic acid methyl ester 1 (b)

Intermediate 1 (a) (0.29 g, 1.38 MMOL) was added to an ice-cold solution of HBr (30% in acetic acid, 1.6 mL) and water (3.0 mL). Sodium nitrite (0.103 g, 1.5 MMOL) in water (2.0 mL) was added dropwise and the mixture stirred at 0 °C for 0.5 hours. Excess nitric acid was destroyed by the addition of urea. The diazonium salt solution was added to a mixture of CuBr (0.6 G, 4.18 MMOL), HBr (30% in acetic acid, 3.5 mL) and water (5.0 mL) at 35 °C and the reaction mixture was heated at 80 °C for 1.5 hours. The resulting precipitate was filtered and washed with water to afford Intermediate 1 (b) (0.307 G) in 81% yield. 1H-NMR (D6-DMSO) : 8 7.99 (d, 1 H, J = 8.8 Hz), 7.85 (d, 1 H, J = 8.8 Hz), 3.94 (s, 3H), 2.39 (s, 3H).

References:

WO2004/63198,2004,A1 Location in patent:Page 69