To a mixed solution of (6S,9aS)-N-benzyl-8-((6-fluoropyridin-2-yl)methyl)-6-((4-hydroxyphenyl)methyl)-4,7-dioxo-2-(prop-2-en-1-yl)-octahydro-1H-pyrazino[2,1-c][1,2,4]triazine-1-carboxamide (30.0 mg, 0.0537 mmol) described in Production Example 2-4 and NMP (2.0 mL) was added a mixture (45.0 mg) of 1-(azetidin-3-yl)-4-ethylpiperazine and benzylbenzene described in Production Example 1-3-2 at room temperature. The resultant mixture was irradiated with a microwave at 140° C. for 8 hours. Water was added to the reaction mixture, the resultant solution was extracted with ethyl acetate, and an organic layer was washed with saturated brine. An organic layer was dried over anhydrous magnesium sulfate and then filtrated. The solvent was evaporated under a reduced pressure, the resultant residue was purified by NH silica gel column chromatography (ethyl acetate:methanol=20:1), and was then further purified by NH silica gel thin-layer chromatography (ethyl acetate). The resultant product was further purified by silica gel thin-layer chromatography (methanol) and was then filtrated using a NH silica gel to give the title compound (14.0 mg, yield: 37%).
