1,5,6,7-Tetrahydro-4H-indol-4-one → Tetrahydroindole

Participants

Reaction Conditions

Reaction Steps

4-oxo-4,5,6,7-tetrahydroindole 5.15 g (38.1 mmol) was gradually added to a stirred slurry of lithium aluminum hydride 4.0 g in anhydrous THF 0.45 L with cooling on ambient water bath, portion-wise, over 30 min period. The mixture was then placed on oil bath and refluxed under Ar on a 75-80° C. oil bath for 26 hours. The reaction mixture was cooled on ambient water bath, quenched by sequential addition of ethyl acetate 4 mL followed by dropwise water addition, 4 mL (very slowly, gas evolution), followed by 15% wt NaOH solution 12 mL followed by additional water 4 mL. The resulting slurry was stirred vigorously for 30 min, the salts were removed by filtration (the cake was washed thoroughly with THF) and the filtrates were concentrated on a rotovap. The oily residue was distilled on highvac using a short-path distillation apparatus, to provide 3.83 g (84%) of tetrahydroindole as oily liquid that turns yellow on light and air exposure, by 57-60° C./0.7 Torr.

Provenance & Evidence