OXAZEPINE DERIVATIVE CRYSTAL OR SOLVATE CRYSTAL THEREOF

Abstract

The present invention provides a crystal of an oxazepine derivative or a crystal of a solvate thereof, having excellent orexin type 2 receptor agonist activity and being useful for the prevention or treatment of, for example, narcolepsy, idiopathic hypersomnia, or hypersomnia. It is a crystal of a compound represented by formula (I) where R1 represents a methyl group or a methyl group substituted with 1 to 3 F atoms; and R2 and R3 each independently represent an H atom or an F atom, or a crystal of a solvate of the compound represented by formula (I).