5-[(3aS,4R,5R,6aS)-5-(tert-Butyl-dimethyl-silanyloxy)-4-[(E)-(3S,4S)-3-(tert-butyl-dimethyl-silanyloxy)-4-methyl-oct-1-en-6-ynyl]-hexahydro-pentalen-(2E)-ylidene]-pentanal