ethyl 3-(3-phenylurea)-2,3-dideoxy-4,5:7,8-di-O-isopropylidene-2,2-dimethyl-α-D-mannono-3,6-furanose-3-octulosonate                                                                                                                                                              在
                                                                                                                                                                                 
sodium methylate                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
甲醇                                                                                  为溶剂,
                                                                                                                                                    反应 48.0h,
                                                                                                                以89%的产率得到[2S,3R,4R,5R]-2-[(4R)-2,2-dimethyl-1,3-dioxolan-4-yl]-3,4-isopropylidenedioxy-10-dimethyl-1-oxa-6,8-diazaspiro-[4,6]-decane-7,9-dione