Toluene → isopropyl 7-bromo-3-oxo-3,4-dihydroquinoxaline-1(2H)-carboxylate

Participants

Reaction Steps

To a solution of 7-bromo-3-oxo-3,4-dihydroquinoxaline (6.8 g, 30 mmol) in pyridine (50 ml) was added a solution of isopropyl chloroformate in toluene (35 ml, 1M, 35 mmol) over 30 minutes. The mixture was triturated with water/chloroform, the organic layer was separated, washed with brine, dried over magnesium sulfate, and evaporated to obtain crude isopropyl 7-bromo-3-oxo-3,4-dihydroquinoxaline-1(2H)-carboxylate (9.3 g, 97%). A sample was recrystallized from ethanol: m p. 159-161° C. 1H-NMR (DMSO-d6) δ 1.25 (d, J=6.2 Hz, 6H), 4.25 (s, 2H), 4.90 (sep, J=6.2 Hz, 1H), 6.89 (d,J=8.6 Hz, 1H), 7.27 (dd,J=9.1, 2.1 Hz, 1H), 7.74(s, 1H), 12.51 (s, 1H), MS (ESI) m/z 330/332 (M+NH4)+.

Provenance & Evidence