3-(4-(trifluoromethyl)phenyl)dihydro-2H-pyran-4(3H)-one 、
N-(氯甲酰)异氰酸酯 以to give 8-(4-(trifluoromethyl)phenyl)-7,8-dihydropyrano[3,4-e][1,3]oxazine-2,4(3H,5H)-dione (Intermediate Z(3))的产率得到8-(4-(trifluoromethyl)phenyl)-7,8-dihydropyrano[3,4-e][1,3]oxazine-2,4(3H,5H)-dione