Acetic Anhydride → HCID 18663644, compound

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Reaction Steps

A solution of 3-chloro-4-{[2-(1,1-dimethyl-propylamino)-3,4-dioxo-cyclobut-1-enylamino]-methyl}-benzonitrile (0.829 g, 2.50 mmol, Example 76) in tetrahydrofuran (10 mL) and N,N-dimethylformamide (5 mL) was treated with sodium hydride (0.066 g, 2.75 mmol) and stirring was continued for 15 minutes. Acetic anhydride (0.281 g, 2.75 mmol) was added. After stirring 40 minutes at room temperature, solvent was removed and the residue was partitioned between ethyl acetate and brine, and the brine fraction was extracted with ethyl acetate. The combined ethyl acetate fractions were washed with dilute, aqueous sodium carbonate solution, with brine and dried (anhydrous sodium sulfate). Removal of solvent gave a yellow solid that was chromatographed (gravity, chloroform) on silica. The appropriate fractions were freed of solvent and the foamy residue was solidified by addition-rotoevaporation of hexane (twice). Recrystallization (twice) of the solid from acetone-hexane gave 513 mg of the title compound as a white solid: mp 150.5°-151.0° C. (softens 149.5° C.); 1H NMR (DMSO-d6) δ7.90-9.22 (broad hump, 1H), 8.10 (s, 1H), 7.84 (m, 1H), 7.51 (d, 1H), 5.29 (br s, 2H), 2.16 (s, 3H), 1.71 (q, 2H), 1.35 (s, 6H), 0.85 (t, 3H) ppm. IR (KBr): 3300, 3080, 2230, 1790, 1720, 1680 cm-1. MS (m/z) 373/375 (M+). HPLC indicates a major component (>99%).

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