Dithiocarbonic acid O-{(4S,6S)-4-[2-(tert-butyl-dimethyl-silanyloxy)-ethyl]-2,2-dimethyl-6-pent-4-enyl-[1,3]dioxan-5-yl} ester S-methyl ester

(R)-6-{(4R,5R)-5-[(Z)-5-(tert-butyldimethylsilyloxy)pent-2-enyl]-2,2-dimethyl-1,3-dioxolan-4-yl}-1-[(4S,6S)-2,2-dimethyl-6-(pent-4-enyl)-1,3-dioxan-4-yl]heptan-3-one