Phosgene → 1-Isocyanato-3,5-dimethoxybenzene

Participants

Reaction Steps

A mixture of 3,5-dimethoxyaniline (8.4 g) in toluene (100 ml) was dropwise added to a toluene solution containing 20 g of phosgene at 10° to 20° C. The resulting mixture was gradually heated and, after being refluxed for 30 minutes, cooled to room temperature. The solvent was removed by distillation under reduced pressure to give (3,5-dimethoxy)phenyl isocyanate (9.8 g). The thus obtained crude substance was added to a methanol solution (50 ml) containing triethylamine (1 g). The resultant mixture was allowed to stand at room temperature for 12 hours, poured into ice-water and extracted with ethyl acetate. The extract was washed with water, dried over magnesium sulfate and concentrated under reduced pressure. The residue was purified by silica gel chromatography using a mixture of benzene and tetrahydrofuran as the eluent to give methyl N-(3,5-dimethoxyphenyl)carbamate (10.2 g) in a yield of 88% (calculated from the starting 3,5-dimethoxyaniline). M.P., 64.5°-65° C.

Provenance & Evidence