(1aS,4aS,8aS)-3,8,8-Trimethyl-2,4a,5,6,7,8-hexahydro-1aH-1-oxa-cyclopropa[d]naphthalene-4-carboxylic acid methyl ester                                                                                                                                                              在
                                                                                                                                                                                 
三氟化硼乙醚                                                                                                                                  作用下,
                                                                                                                以
                                                                                         
二氯甲烷                                                                                  为溶剂,
                                                                                                                                                                                        以79%的产率得到(2aS,5aR,8aR)-1,1,4-Trimethyl-2a,3,5a,6,7,8-hexahydro-2-oxa-cyclobuta[d]indene-5-carboxylic acid methyl ester