5,7-Dimethoxy-2-oxo-2H-chromene-3-carboxylic acid 2-trimethylsilanyl-ethyl ester   、                                                                                      
3-甲基-1-丁烯                                                                                                                                                                                              以
                                                                                         
苯                                                                                  为溶剂,
                                                                                                                                                                                        生成                                                 2-(trimethylsilyl)ethyl rac-(1R,2aS,8bS)-1,8b-dihydro-1-(1-methylethyl)-6,8-dimethoxy-3-oxo-2H-benzo[b]cyclobuta[d]pyran-2a(3H)-carboxylate   、                                                                                             2-(trimethylsilyl)ethyl rac-(1S,2aS,8bS)-1,8b-dihydro-1-(1-methylethyl)-6,8-dimethoxy-3-oxo-2H-benzo[b]cyclobuta[d]pyran-2a(3H)-carboxylate