4-(3-Oxo-butyl)-5H-furan-2-one

2-methyl-1,7-dioxaspiro[4.4]nonan-8-one

3-Oxo-2-(5-oxo-2,5-dihydro-furan-3-ylmethyl)-butyric acid ethyl ester

3-Oxo-2-(5-trimethylsilanyl-furan-3-ylmethyl)-butyric acid ethyl ester

2-trimethylsilyl-4-(1,3-dithian-2-yl)-furan