Hydrogen Bromide → 2-(4-Bromo-3-oxobutyl)-1H-isoindole-1,3(2H)-dione

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Reaction Steps

Oxalyl chloride (5.8 ml; 66.7 mmol) is added to Pht-β-Ala-OH (9.96 g; 44.5 mmol) dissolved in dichloromethane (120 ml) and 3 drops of dimethylformamide (DMF). The mixture is stirred for 3 hours at ambient temperature. After elimination of the solvent, the white solid is taken up in a 1:1 mixture of anhydrous tetrahydrofuran and acetonitrile (200 ml) then 49 ml of a 2 M solution of (trimethylsilyl) diazomethane in hexane (97.9 mmol) are added dropwise at 0° C. The solvents are eliminated after one night of stirring at 0° C. The pale yellow solid is then dissolved in dichloromethane (60 ml) and 12 ml of aqueous hydrobromic acid (48%) is added dropwise at 0° C. The mixture is stirred until the temperature reaches 15° C. and 50 ml of a saturated solution of sodium bicarbonate is added. The organic phase is washed with salt water then dried over sodium sulphate. Crystallization from diethyl ether allows a white solid to be obtained (11.39 g; yield=86%).

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