Diphosgene → 5-Chloro-3-methyl isatoic anhydride

Participants

Reaction Conditions

Reaction Steps

To a suspension of 2-amino-3-methyl-5-chlorobenzoic acid (i.e. product of Example 6, Step A) (97 g, 520 mmol) stirred, in dry dioxane (750 mL) at room temperature, trichloromethyl chloroformate (63 g, 320 mmol) was added dropwise. The reaction mixture exothermically warmed slowly to 42° C., and the solid almost completely dissolved before a thick suspension formed again. After the suspension was stirred at ambient temperature for 2.5 hours, the title compound was isolated by filtration, washed with ethyl ether, and dried to yield the title product compound, obtained as a white solid (98 g). 1H NMR (DMSO-d6) δ 2.3 (s, 3H), 7.70 (s, 1H), 7.75 (s, 1H), 11.2 (s, 1H).

Provenance & Evidence