Carbon Dioxide → 10-Bromo-5,6-dihydrobenzo[F]imidazo[1,2-D][1,4]oxazepine-2-carboxylic acid

Participants

Reaction Conditions

Reaction Steps

Into a 20 L 4-necked round-bottom flask purged and maintained with an inert atmosphere of nitrogen was placed a solution of 9-Bromo-2-iodo-4,5-dihydro-6-oxa-1,3a-diaza-benzo[e]azulene (700 g, 1.79 mol, 1.00 equiv) in tetrahydrofuran (13 L), followed by the addition of EtMgBr (1400 mL) dropwise with stirring at −30° C. over 60 min. To the above an excess of CO2 (gas) was introduced in over 3 h at −78° C. The resulting solution was warmed to room temperature naturally. The pH value of the solution was adjusted to 3 with hydrogen chloride (2 mol/L). The precipitates were collected by filtration, washed with 2×100 mL of EA and dried in a vacuum oven to afford 410 g (74%) of 9-Bromo-4,5-dihydro-6-oxa-1,3a-diaza-benzo[e]azulene-2-carboxylic acid as a white solid.

Provenance & Evidence