Synthesis, Characterization, and Crystal Chemistry of Tasimelteon, a Melatonin Agonist, in Its Anhydrous and Hemihydrate Forms.

Two crystalline forms of tasimelteon, a drug approved by the U.S. Food and Drug Administration for the treatment of non-24-h sleep-wake disorder, have been studied by single crystal and powder diffraction analyses, thermogravimetric analysis, differential scanning calorimetry, spectroscopic, and optical methods.