Methyl p-toluenesulfonate → 5-Carboxy-2,3-dimethylbenzoxazolium p-toluene-sulfonate

Participants

Reaction Conditions

Reaction Steps

5-Carboxy-2-methylbenzoxazole (8.9 g) and methyl-p-toluenesulfonate (11.16 g) were combined and heated to 200° C. with stirring for 10 minutes. The mixture became a brown liquid and mild boiling occurred. The reaction was cooled to room temperature and the liquid solidified. Acetone (50 ml) was added, and with constant heating at reflux, the product was broken up with a spatula. The resulting slurry was heated at reflux for 15 minutes with rapid stirring and the off-white product was collected by filtration. This product was slurried again in refluxing acetone for 30 minutes, filtered, washed with ligroin P950, and dried to yield 9.3 g of 5-carboxy-2,3-dimethylbenzoxazolium p-toluene-sulfonate (Intermediate D).

Provenance & Evidence