1,5-Diacetylindoline → 1-(1-acetyl-2,3-dihydro-1H-indol-5-yl)-2-bromoethanone

Participants

Reaction Steps

To a suspension of 1,5-diacetylindoline (10.0 g, 49.2 mmol) in 90 mL of THF at rt was added pyridinium tribromide (16.52 g, 51.7 mmol, 1 equiv) as solids portionwise over a period of 10 min. When there was still about 1.5 g of pyridinium tribromide left, the mixture solidified. Added another 30 mL of THF to make the mixture stirrable again. The remaining 1.5 g tribromide was added in one portion. The mixture was stirred at rt (no exotherm as checked by a thermometer). After 1.5 h, LCMS showed conversion complete. The suspension was filtered. The cake was washed with THF (2×30 mL), and then water (2×50 mL). The wet cake was sucked under house vacuum at rt for 2 days to give 1-(1-acetyl-2,3-dihydro-1H-indol-5-yl)-2-bromoethanone (12.89 g) as light grey solids. LC-MS (ES) m/z=281.9, 283.9.

Provenance & Evidence