(S)-octalone

(S)-7-Methyl-7-(3-oxo-butyl)-1,4-dioxa-spiro[4.5]decan-8-one

[1R]-1-methyl-1(3-butanone)-3-ethylenedioxy-2-oxocyclohexanone

ethyl 5,5-ethylenedioxy-3-methyl-2-oxocyclohexanecarboxylate