The product from Example 106A (1.17 g), diisopropylethyl amine (2.5 mL, 14.4 mmol) and 1,2,4,5-benzenetetracarboxylic dianhydride (0.78 g, 3.58 mmol) in THF (30 mL) were processed as described in Example 1B. The reaction mixture was treated with saturated Na2CO3 solution (30 mL), and stirred vigorously at room temperature for 1 hour. The layers were separated and the aqueous layer was acidified with 1N HCl. The acidified aqueous layer was evaporated under reduced pressure to afford off-white plates. Soxhlet extraction (ethanol) of the crude solid, followed by RP-HPLC, provided the title compound (20 mg).
