2-Methylbenzenesulfonic acid hydrate → 2-(1-(4-Bromophenyl)-3-oxocyclobutyl)isoindoline-1,3-dione

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Reaction Steps

A mixture of 2-[2-(4-bromophenyl)-5,8-dioxaspiro[3.4]oct-2-yl]-1H-isoindole-1,3(2H)-dione (8-2) (3.1 g, 7.48 mmol) and Toluenesulfonic acid monohydrate (0.14 g, 0.75 mmol) in acetone (50 mL) was refluxed for 2 days. The cooled mixture was diluted with EtOAc, washed with sat. NaHCO3, dried (MgSO4), filtered, and concentrated under reduced pressure. The residue was purified by silica gel chromatography, eluting with 0˜100% EtOAc in hexane, to give 2-[1-(4-bromophenyl)-3-oxocyclobutyl]-1H-isoindole-1,3(2H)-dione (8-3) as a colorless form.

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