7-chloro-1-(2,4-difluorophenyl)-1,4-dihydro-8-methyl-6-nitro-4-oxoquinolone-3-carboxylic acid 、
4-哌啶酮缩乙二醇 在
potassium carbonate 作用下,
以
二甲基亚砜 为溶剂,
以89%的产率得到1-(2,4-difluorophenyl)-1,4-dihydro-7-(1,4-dioxa-8-azaspiro[4.5]dec-8-yl)-8-methyl-6-nitro-4-oxoquinoline-3-carboxylic acid