prop-2-en-1-yl (1S,6aS,6R)-5-{[(3S,5S)-5-[(dimethylamino)carbonyl]-1-({[(4-nitrophenyl)methyl]oxy}carbonyl)pyrrolidin-3-yl]sulfanyl}-6-methyl-2-oxo-1-[(2R)-4,4,5,5-tetramethyl-3-oxa-4-silahex-2-yl]-1,2,6,6a-tetrahydroazeto[1,2-a]pyrrole-4-carboxylate