Ethyl isocyanate → 1-Ethyl-3-[2-(2-methyl-7,8-dihydro-6H-indeno[5,4-d][1,3]oxazol-8-yl)ethyl]urea

2-(2-Methyl-7,8-dihydro-6H-indeno[5,4-d][1,3]oxazol-8-yl)ethanamine hydrochloride (156 mg, 0.617 mmol) and triethylamine (86.1 mL, 0.617 mmol) were dissolved in tetrahydrofuran (6.2 mL), ethyl isocyanate (58.6 μL, 0.741 mmol) was added under ice-cooling, and the mixture was stirred for 15 min. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (ethyl acetate) to give the title compound (20.2 mg, yield 11%).