t-4-acetoxy-5-hydroxy-r-5-[[(tert-butyldimethylsilyl)oxy]methyl]-2-cyclopentenone

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

2-羟基甲基-2-环戊酮