Dimethylformamide → 3,5,5-Trimethyl-4-oxo-4,5,6,7-tetrahydroindole-2-carboxaldehyde

Participants

Reaction Steps

POCl3 1.2 mL (13.1 mmol) was added dropwise into anhydrous DMF 15 mL with cooling on ice bath. After 10 minutes, a solution of 3,5,5-trimethyl-4-oxo-4,5,6,7-tetrahydroindole 1.500 g (8.463 mmol) in anh. DMF was added dropwise over a 10 min period. The cooling bath was allowed to expire and the reaction was stirred at ambient temperature overnight (11 hours). With cooling on ice bath, the reaction mixture was quenched by addition of crushed ice and ice-cold water (approx 150 mL total). The reaction mixture was then alkalized to pH=10 (approximately, on pH paper strip) by gradual addition of potassium carbonate solution, the total volume was adjusted to about 250 mL with additional water and the mixture was stirred at ambient temperature for 1 day. The resulting slurry was cooled on ice bath, the precipitated product was collected by filtration, washed with ice-cold water, dried by suction and on highvac. Y=1.351 g (77.5%) of a white microcrystalline solid. 1H-NMR (d6-DMSO, 400 MHz): 12.14 (br s, 1H), 89.66 (s, 1H), 2.79 (t, 6.1 Hz, 2H), 2.48 (s, 3H), 1.86 (t, 6.3 Hz, 2H), 1.06 (s, 6H)

Provenance & Evidence