1-benzyl-2,3-dihydroindole-5-carbaldehyde → 5-Methylindoline

Participants

Reaction Steps

Into a 200 mλ pressure resistant reactor (autoclave) equipped with a stirrer, 20 g (0.084 mol) of 1-benzyl-5-formylindoline and 100 mλ of ethanol were charged, and the interior of the reactor was flushed with nitrogen. 2 g of 10% Pd/C was introduced, and the reactor was closed, whereupon hydrogen was introduced from a hydrogen supply pipe and reacted at 80° C. for 6 hours while adjusting the initial pressure of hydrogen in the reactor to be 6 2 kg/cm. Upon confirming the ceasing of absorption of hydrogen, the reaction was terminated. Then, the reaction solution was cooled to room temperature, and the hydrogen was released, and the palladium catalyst (10% Pd/C) was collected by filtration, and ethanol was distilled off under reduced pressure to obtain a colorless liquid as the residue. The obtained liquid was subjected to vacuum distillation to obtain 9.5 g of 5-methylindoline having a boiling point of from 56 to 57° C./0.3 mmHg. The yield was 85% (based on 1-benzyl-5-formylindoline).

Provenance & Evidence