The general procedure for the synthesis of 2-(3-bromo-2,2-dimethylpropyl)isoindoline-1,3-dione from 3-hydroxy-1H-isoindol-1-one and 3-bromo-2,2-dimethylpropan-1-ol was as follows: first, 2,3-dihydro-1H-isoindoline-1,3-dione (3.1 g, 21.07 mmol, 1.00 equiv.) and 3-bromo-2,2- dimethylpropan-1-ol (3.4 g, 23.2 mmol) was dissolved in an appropriate amount of solvent. A solution of triphenylphosphine (10.9 g, 41.56 mmol, 2.00 eq.) in tetrahydrofuran (THF, 100 mL) was slowly added dropwise at 0 °C and under nitrogen protection, followed by diisopropyl azodicarboxylate (8.3 g, 41.09 mmol, 2.00 eq.). The reaction mixture was stirred at 25 °C for 12 hours. After completion of the reaction, the mixture was concentrated under reduced pressure to remove the solvent. The crude product was purified by silica gel column chromatography using ethyl acetate/petroleum ether (1:50 v/v) as eluent. The final product was 3.2 g of 2-(3-bromo-2,2-dimethylpropyl)-2,3-dihydro-1H-isoindole-1,3-dione in 51% yield as a colorless oil.
