Trifluoroacetic acid → 2-(5-(Methylsulfonamido)-2,3-dioxoindolin-1-yl)acetic acid

Participants

Reaction Conditions

Reaction Steps

A solution of methyl 2-(5,5-dimethyl-5′-(methylsulfonamido)-2′-oxospiro[[1,3]dioxane-2,3′-indoline]-1′-yl)acetate (200 mg, 0.502 mmol) in dioxane/water 1:1 (7 ml) and TFA (0.193 ml, 2.510 mmol) was stirred at 80° C. overnight. TFA (0.271 ml, 3.51 mmol) was freshly added and stirring at 80° C. was continued for 24 hours. Then TFA (0.155 ml, 2.008 mmol) was freshly added and stirring at 80° C. was continued for additional 48 hours. The volatiles were removed under vacuum and the crude was purified by flash chromatography on silica gel (DCM:MeOH from 99.5:0.5 to 7:3+0.5% AcOH), affording 2-(5-(methylsulfonamido)-2,3-dioxoindolin-1-yl)acetic acid (143 mg, 0.479 mmol, 96% yield). MS/ESI+ 298.9 [MH]+.

Provenance & Evidence