4,5,7,8-tetrahydro-9-hydroxy-6,10-dioxo-5-methyl-9-ethylbicyclo<4.2.1>nonano<3,4-b>furan-3-carboxylic acid methyl ester                                                                                                                                                              在
                                                                                                                                                                                 
对甲苯磺酸                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
苯                                                                                  为溶剂,
                                                                                                                                                    反应 5.0h,
                                                                                                                以98%的产率得到4,5,7,8-tetrahydro-6,10-dioxo-5-methyl-9-ethylidenebicyclo<4.2.1>nonano<3,4-b>furan-3-carboxylic acid methyl ester