Dihydrofukinolide

(S)-2-Methylbutyric acid (3R)-1',3,3',3'aα,4,4',5,5',6',7'-decahydro-3'α-acetoxy-7'α,7'aα-dimethyl-4-methylene-2-oxospiro[furan-3(2H),2'-[2H]inden]-4'β-yl ester