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

2-[[tert-butyl(dimethyl)silyl]oxymethyl]cyclopent-2-en-1-one

ethyl 5-oxocyclopentene-1-carboxylate