2-hydroxy-2-[[(tert-butyldimethylsilyl)oxy]methyl]cyclopent-4-ene-1,3-dione

2,2-Dimethyl-1,3-dioxa-spiro[4.4]non-7-ene-6,9-dione

6-carbethoxy-1,4-dioxaspiro[4.4]non-6-ene

6-溴-1,4-二氧杂螺[4.4]壬-6-烯

2-溴-2-环戊酮