Patent ID: 8609871

Claim:
A process for producing crystals of (S)-N-[2-(1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl)ethyl]propionamide, which comprises: step (a): a step for propionylating the amino group of (S)-N-[2-(1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-yl)ethylamine or a salt thereof obtained by a process comprising: step (i): a step for asymmetrically reducing (E)-2-(1,6,7,8-tetrahydro-2H-indeno[5,4-b]furan-8-ylidene)ethylamine or a salt thereof with a catalyst, and step (ii): a step for catalytically reducing the reaction product obtained in step (i) at a reaction temperature of 40° C. to 100° C. and a pH 3 to 9 with a catalyst, and step (b): a step for crystallizing by adding water to the reaction solution obtained in step (a) in a ratio 0.5 to 5 times by volume based on the reaction solution at a temperature of −20 to 60° C.