Step 2. Preparation of 3-(1,3-dioxoisoindolin-2-yl)propanal
A mixture of 2-(3-hydroxypropyl)isoindoline-1,3-dione (2.0 g, 8.76 mmol) with IBX (8.2 g, 29.27 mmol) in 60 mL of ethyl acetate (EA) was refluxed for 2 hours. After completion of the reaction, the mixture was filtered and the filtrate was concentrated to afford 3-(1,3-dioxoisoindolin-2-yl)propionaldehyde (2.0 g, yield: 100%) as a white solid.
NMR (500 MHz, CDCl3): δ 9.82 (s, 1H), 7.84-7.86 (m, 2H), 7.72-7.74 (m, 2H), 4.04 (t, J = 7.0 Hz, 2H), 2.87-2.89 (m, 2H) ppm.
MS (ESI): m/z 553.7 [M + 1]+.
