2,2-Dimethyl-propionic acid (S)-5-[(S)-(tert-butyl-dimethyl-silanyloxy)-((R)-2,2-dimethyl-[1,3]dioxolan-4-yl)-methyl]-4-(2-diazo-acetyl)-2-oxo-2,5-dihydro-furan-3-yl ester

(S)-1-((3aS,4S,5R,6R,7S,7aS)-6-allyl-5-hydroxy-2,2,2',2'-tetramethyltetrahydro-5H-spiro[benzo[d][1,3]dioxole-4,4'-[1,3]dioxolan]-7-yl)-2-(dimethylamino)-2-oxoethyl pivalate