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

Participants

Reaction Steps

A solution of methyl 2-(aminosulfonyl)-4-(methylthio)benzoate (5.23 g, 20.0 mmol), n-butyl isocyanate (2.25 mL, 20.0 mmol), and 1,4-diaza[2.2.2]bicyclooctane (0.09 g, 0.8 mmol) in mixed xylenes (50 mL) 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 2-(isocyanatosulfonyl)-4-(methylthio)benzoate as a yellow oil (6.4 g). This was used immediately without further purification or characterization.

Provenance & Evidence