3-(3,4-dihydro-7-fluoro-3-oxo-2H-1,4-benzoxazin-6-yl)-6-methyl-2,4(1H,3H)-pyrimidinedione   、                                                                                      
氯乙腈                                                                                                                                                                                                                                                                                                          以there is obtained 3-(2-cyanomethyl-3,4-dihydro-7-fluoro-3-oxo-2H-1,4-benzoxazin-6-yl)-6-methyl-2,4(1H,3H)-pyrimidinedione, m.p.>230° C.的产率得到3-(2-cyanomethyl-3,4-dihydro-7-fluoro-3-oxo-2H-1,4-benzoxazin-6-yl)-6-methyl-2,4(1H,3H)-pyrimidinedione