p-Toluenesulfonic acid → 5'-(pyrrolidin-1-ylsulfonyl)spiro[1,3-dioxane-2,3'-indol]-2'(1'H)-one

Participants

Reaction Steps

A stirred mixture of 5-(pyrrolidin-1-ylsulfonyl)-1H-indole-2,3-dione (0.88 g, 3.14 mmol), 1,3-propanediol (0.92 mL, 1.26 mmol, 4 eq) and p-toluenesulfonic acid (1.19 g, 6.28 mmol, 0.2 mole % ) in benzene (100 mL) was refluxed with a Dean Stark Trap for 6 hours. The reaction was cooled to room temperature, washed with sat. aq. NaHCO3 (1×), water (2×), and brine (1×), dried over NaHCO3 (1×,), filtered and concentrated. The crude product was purified on Biotage KP silica gel eluting with 90/10 CH2Cl2/EtOAc to give the title compound as a white solid (0.72 g, 68% ). NMR (300 Mz, DMSO-d6): consistent. MS: (API-ES+) 338 [M+H] consistent.

Provenance & Evidence