Isoamyl Nitrite → 6-Benzothiazolecarboxylic acid, 4-methoxy-, methyl ester

HRID 1643820Notes

Reaction equation

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]([O:15][CH3:16])[C:5]=2[N:6]=1.N(OCCC(C)C)=O>CN(C=O)C>[CH3:16][O:15][C:7]1[C:5]2[N:6]=[CH:2][S:3][C:4]=2[CH:10]=[C:9]([C:11]([O:13][CH3:14])=[O:12])[CH:8]=1

Participants

Conditions

Temperature: 65 °C

Procedure

To a stirred solution of methyl 2-amino-4-methoxy-1,3-benzothiazole-6-carboxylate (100 g, 0.42 mol) in DMF (1 L) was added drop wise isoamyl nitrite (108 g, 0.92 mol) at 65° C. Then the resulting mixture was stirred at 65° C. for 20 min. TLC (EtOAc/Petroleum ether 1:4) showed the reaction was complete. After cooling to ambient temperature, the mixture was poured into ice water (1 L). The resulting mixture was extracted with EtOAc (1 L×3). The combined organic layers were washed with water (1 L×2), dried over Na2SO4 and concentrated in vacuum. The residue was purified by chromatography (silica gel, EtOAc/Petroleum ether 1:50 to 1:10) to afford the product (22 g, 23%) as a yellow solid. 1H NMR (400 MHz, CDCl3): δ 9.050 (s, 1H), 8.285-8.281 (d, 1H), 7.592-7.587 (d, 1H), 4.110 (s, 3H), 3.965 (s, 3H).

Workup

temperatureAfter cooling to ambient temperature
extractionThe resulting mixture was extracted with EtOAc (1 L×3)
washThe combined organic layers were washed with water (1 L×2)
dry with materialdried over Na2SO4
concentrationconcentrated in vacuum
customThe residue was purified by chromatography (silica gel, EtOAc/Petroleum ether 1:50 to 1:10)

Sources & evidence

ORD record: ord-b7e8c6bc0e324514991afd7f7c1d7c9b
Source dataset: uspto-grants-2012_02
DOI: 10.6084/m9.figshare.5104873.v1
Patent number: US08119624B2

Reaction notes

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