ethyl 4-(3-chlorophenyl)-2-hydroxy-5-oxo-2-(trifluoromethyl)-2,3,4,5,6,7-hexahydrocyclopenta[b]pyran-3-carboxylate                                                                                                                                                              在
                                                                                                                                                                                 
对甲苯磺酸                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
甲苯                                                                                  为溶剂,
                                                                                                                                                    反应 12.0h,
                                                                                                                以71%的产率得到ethyl 4-(3-chlorophenyl)-5-oxo-2-(trifluoromethyl)-4,5,6,7-tetrahydrocyclopenta[b]pyran-3-carboxylate