Phosgene → Methyl 4-ethoxy-2-(isocyanatosulfonyl)benzoate

Participants

Reaction Steps

A solution of methyl 2-(aminosulfonyl)-4-ethoxybenzoate (7.56 g, 29.2 mmol), n-butyl isocyanate (3.29 mL, 29.2 mmol), and 1,4-diaza[2.2.2]bicyclooctane (0.13 g, 1.2 mmol) in mixed xylenes was heated at reflux for 10 minutes. Phosgene was then added at such a rate that the internal temperature stayed at 133° C. or above. When consumption of phosgene ceased, the solution was cooled to room temperature and then filtered under nitrogen. Rotary evaporation gave methyl 4-ethoxy-2-(isocyanatosulfonyl)benzoate as a cloudy yellow oil (8.2 g). This was used immediately without further purification or characterization.

Provenance & Evidence