5-Bromo-2-ureidothiophene-3-carboxamide synthesis

Yield:354812-10-5 71%

Reaction Conditions:

with N-Bromosuccinimide in tetrahydrofuran at 0 - 20; for 16 h;Inert atmosphere;Darkness;

Steps:

1-(5-Bromo-3-carbamoylthiophen-2-yl)urea (8):

To a solution of 1-(3-carbamoylthiophen-2-yl)urea (140 mg, 0.756 mmol) in THF (9 mL) was added NBS (149 mg, 0.832 mmol) and the mixture was stirredat 0 °C for 1 h under shielding light. The reaction mixture was stirred at rt for 15 h, and concentrated. Purification by chromatography (20 g, CHCl₃: MeOH = 10:1) gave compound 8 (140.9 mg, 0.534 mmol, 71%) as pink powder; mp 221-222 °C (decomposed); ¹H NMR (400 MHz, CD₃OD) δ 7.24 (s, 1H), ¹³C NMR (100 MHz, CD₃OD) δ 168.6, 157.1, 151.5, 125.9, 113.4, 103.2; FT-IR (neat) 3352, 3193, 1702, 1546, 1511, 1420, 1328, 1275, 1220, 771, 694 cm^-1; MS (FAB) m/z 91 (100), 263 [(M+H)⁺], 265[(M+H+2)⁺]; HRMS (FAB) calcd for C₆H₆⁷⁹BrN₃O₂S [(M+H)⁺] 263.9438, found 263.9440, calcd for C₆H₆⁸¹BrN₃O₂S [(M+H+2)⁺] 265.9410, found 265.9416.

References:

Kawasaki, Norihiko;Fukuda, Hayato;Ishihara, Jun [Heterocycles,2020,vol. 101,# 2,p. 707 - 716]