Methanesulfonic Acid → Phthalimide

Temperature

70 °C

To a stirred solution of acetic anhydride (5.0 mL, 53.0 mmol) and 7.7 wt % phosphorus pentoxide in methanesulfonic acid (Eaton's Reagent) (5.0 mL, 4.60 mmol) was added 2-(3-oxobutyl)isoindoline-1,3-dione (1.0 g, 4.60 mmol). The reaction was heated at 70° C. and for 8 h. The reaction was allowed to cool to room temperature and maintained overnight. The reaction was diluted with EtOAc, washed with ice cold water, dried (Na2SO4), filtered and concentrated under vacuum. The residue was purified by silica gel chromatography (Analogix, SF40-115 g, 20-100% EtOAc in hexanes). The pure fractions were combined and evaporated to dryness and triturated with 10% EtOAc in hexanes, filtered and evaporated to dryness to give 2-(2,6-dimethyl-4-oxo-4H-pyran-3-yl)methyl)isoindoline-1,3-dione (290 mg, 1.024 mmol, 22.24% yield) as a yellow solid. 1H NMR (400 MHz, DMSO-d6) δ 7.91-7.74 (m, 4 H), 6.06 (s, 1 H), 4.54 (s, 2 H), 2.43 (s, 3 H), 2.22 (s, 3 H). MS(ES) [M+H]+ 284.0.

1. temperatureto cool to room temperature
2. temperaturemaintained overnight
3. washwashed with ice cold water
4. dry with materialdried (Na2SO4)
5. filtrationfiltered
6. concentrationconcentrated under vacuum
7. customThe residue was purified by silica gel chromatography (Analogix
8. customevaporated to dryness
9. customtriturated with 10% EtOAc in hexanes
10. filtrationfiltered
11. customevaporated to dryness

ORD record

ord-86a81e7ba5e140e19d116f530394757f

Source dataset

uspto-grants-2016_07

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09382234B2