N[C:2]1[S:3][C:4]2[CH:10]=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:8]=[C:7]([CH3:15])[C:5]=2[N:6]=1.NC1C=CC(C(OC)=O)=CC=1C.[Br:28]Br>CC(O)=O>[Br:28][C:2]1[S:3][C:4]2[CH:10]=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:8]=[C:7]([CH3:15])[C:5]=2[N:6]=1Methyl 2-amino-4-methyl-benzothiazole-6-carboxylate (I-16A). Into a 500-mL round-bottom flask was placed a solution of methyl 4-amino-3-methylbenzoate (4.00 g, 24.2 mmol, 1.00 equiv) and NaSCN (7.00 g, 86.4 mol, 3.57 equiv) in AcOH (90 mL) that was cooled to 0° C. This was followed by the addition of a solution of Br2 (3.9 g, 25 mmol, 1.0 equiv) in AcOH (25 mL) dropwise, maintaining at 0° C. over 20 min. The resulting solution was allowed to warm to RT on its own accord (over approximately 10 min.) and stirred for 48 hrs at RT. At this time, the solids of the reaction were filtered out. The resulting solution was diluted with 100 mL H2O. The pH value of the solution was adjusted to 8-9 with ammonia (using Whatman PH strip paper to monitor PH adjustment) which furnished an immediate precipitation. The solids were collected by filtration and washed once with ice cold MeOH (50 mL) to afford as a yellow solid. MS m/z 223.0 (M+11). 1H NMR (400 MHz, MeOH-d4) δ 8.17 (app d, J=1.0 Hz, 1H), 8.03 (br s, 2H, NH2), 7.68 (s, 1H), 3.82 (s, 3H), 2.42 (s, 3H).
Loading…
