2'-bromo-1,2',7,7-tetramethyl-4'-methylidenespiro[bicyclo[2.2.1]heptane-2,3'-cyclobutane]-1'-one 、 (4E)-2-bromo-2-methyl-4-(1,7,7-trimethyl-2-bicyclo[2.2.1]heptanylidene)cyclobutan-1-one 生成
1,2',7,7-tetramethyl-4'-methylidenespiro[bicyclo[2.2.1]heptane-2,3'-cyclobutane]-1'-one