1-(2-hydroxymethyl)-1-H-pyrrole-2,5-dione is a synthetic building block for adding an maleimide group with a hydroxyl handle. The hydroxyl group enables further derivatization or replacement with other reactive functional groups.
General procedure for the synthesis of N-(2-hydroxyethyl)maleimide (HEMI) from 3a,4,7,7a-tetrahydro-2-(2'-hydroxyethyl)-4,7-epoxy-1H-isoindole-1,3(2H)-dione (HEMI-A): 0.19 mol (40 g) of HEMI-A was mixed with 227 g of xylene and 0.005 g of methylhydroquinone ( MEHQ, as antioxidant) was mixed. The reaction was heated under nitrogen protection at reflux at 130 °C for 3 h and 15 min to convert HEMI-A to HEMI with a conversion of 98.7% and a reaction yield of about 98.7%. After completion of the reaction, the reactor was cooled to room temperature, the reaction mixture was filtered and the solid product was washed with 15 g of xylene. The washed solid was dried under vacuum to give 25.1 g of HEMI in 93% yield based on HEMI-A. The purity of HEMI was confirmed to be greater than 99% by 1H-NMR analysis. The mother liquor and wash liquor were combined and the total mass was determined to be 230.2 g, which contained 1.17 g of HEMI, which can be recovered or recycled as described above.
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