Synthesis
Isatoic Anhydride is synthesized from indole (9a) by stirring in a 4:1 mixture of DMF/H2O for 16 h at room temperature.
1 H NMR (DMSO-d6): δ11.73 (s, br., 1H), 7.92 (d, J = 7.8 Hz, 1H), 7.74 (t, J = 7.8 Hz, 1H), 7.26 (t, J = 7.8 Hz, 1H), 7.16 (d, J = 7.8 Hz, 1H).
Chemical Properties
BEIGE TO BROWN POWDER
Uses
Isatoic anhydride is a potent inactivator of α-chymotrypsin and inactivates stoichiometrically. Isatoic Anhydride is an important compound in the preparation of serine protease inhibitors.
Preparation
Phosphorus tribromide (0.035 mol) was added to a solution of N-carbethoxy- or N-carbobenzoxy-anthranilic acid (0.1 mol;prepared by coupling anthranilic acid with the corresponding carbalkoxy chloride in the usual way) in anhydrous diethyl ether (100 mL). After 24 h at room temperature, isatoic anhydride had separated as a microcrystalline product. It was collected by filtration, washed with dry diethyl ether, and recrystallized from ethanol. Yield ca. 90%.
Definition
A bicyclic molecule composed of a benzene ring
attached at the oand mpositions to a heterocyclic
ring. It forms useful anthranilic acid derivatives by
reaction with hydrogen.
Flammability and Explosibility
Non flammable
Purification Methods
Recrystallise it from EtOH or 95% EtOH (30mL/g) or dioxane (10mL/g) and dry it in a vacuum. [Wagner & Fegley Org Synth Coll Vol III 488 1955, Ben-Ishai & Katchalski J Am Chem Soc 74 3688 1952, UV: Zentmyer & Wagner J Org Chem 14 967 1949, Beilstein 27 II 299, 27III/IV 3330.]
