Benzothiazole, 2-ethyl-6-nitro- (8CI,9CI) synthesis

Yield:17142-80-2 68%

Reaction Conditions:

with sulfuric acid;HNO₃ at 0; for 2 h;

Steps:

2-Ethyl-6-nitro-1,3-benzothiazole

To a cooled (0 °C) solution of 2-ethyl-1,3-benzothiazole (2.30 g, 14.1 mmol) in concentrated H₂SO₄ (10 mL) fuming HNO₃ (4.44 g, 70.4 mmol) was added dropwise, and the mixture was stirred 2 h at 0 °C. The mixture was concentrated and poured into ice-water. DCM (100 mL) was added, and the phases were separated. The organic phase was washed with aq NaHCO₃ and brine, dried over Na₂SO₄ and evaporated. The residue was purified by column chromatography (PE/EtOAc = 1/0~0/1, silica-CS 40 g, 40 mL/min, silica gel, UV 254 nm) to afford the product (2.00 g, 68 %). ESI-MS m/z calcd for [C₉H₈N₂O₂S] [M+H]⁺: 209.0; found: 209.1.¹H NMR (400 MHz, Chloroform- d) δ 8.75 (d, J = 2.4 Hz, 1H), 8.17 (dd, J = 8.8, 2.0 Hz, 1H), 7.90 (d, J = 8.8 Hz, 1H), 3.14 (q, J = 7.6 Hz, 2H), 1.44 (t, J = 7.6 Hz, 3H).

References:

WO2022/144274,2022,A1 Location in patent:Page/Page column 187