Isocyanate → 1-(5-Chloro-4-nitrothiophen-2-yl)-3-(1-methylpiperidin-4-yl)urea

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Reaction Steps

5-chloro-4-nitrothiophene-2-carbonyl azide (400 mg, 1.23 mmol) from above was dissolved in toluene (10 mL) and the resulting solution was refluxed for 2 hours. After this time, the reaction mixture was cooled to ambient temperature. 1-methylpiperidin-4-amine (155 mg, 1.36 mmol) was added drop-wise to the above solution. The resulting mixture was stirred at ambient temperature for 9 hours. After this time, TLC analysis showed no intermediate isocyanate remaining so the mixture was diluted with ethyl acetate and washed with water and brine. The organic layer was dried (Na2SO4), filtered and the solvent was removed to give the crude residue. The crude material was purified by silica gel chromatography using a 95:5 mixture of dichloromethane and methanol as eluent to afford the title product as a brown solid (200 mg, 51% yield). 1H NMR (400 MHz, d6-DMSO) δ: 10.03 (1H, br), 6.97 (1H, m), 6.86 (1H, s), 3.51 (1H, m), 2.88 (2H, m), 2.77 (1H, m) 2.32 (4H, m), 1.55 (2H, m), 1.23 (2H, m).

Provenance & Evidence