Ethyl 2-butynoate → 2-(4-Cyclohexyl-phenoxymethyl)-5-methyl-2,3-dihydro-oxazolo[3,2-a]pyrimidin-7-one

To a solution of 5-(4-cyclohexyl-phenoxymethyl)-4,5-dihydro-oxazol-2-ylamine (300 mg, 1.095 mmol) in ethanol (6 mL) was added ethyl 2-butynoate (246 mg, 2.19 mmol). The reaction mixture was heated in a microwave oven at 150° C. for 30 min, then at 160° C. for 20 min, and at 170° C. for 30 min. Solvent was removed under vacuum, and the residue purified via flash column chromatography (silica gel, 1-18% EtOH/CH2Cl2) to afford 190 mg of 2-(4-cyclohexyl-phenoxymethyl)-5-methyl-2,3-dihydro-oxazolo[3,2-a]pyrimidin-7-one as a white solid.