(3R,3aS,7aR)-3-[(S)-1-(Isopropyl-dimethyl-silanyloxy)-2-methyl-propyl]-2-(4-methoxy-benzyl)-3a,5,5-trimethyl-1-oxo-octahydro-4-oxa-2-aza-5-sila-indene-3-carboxylic acid methyl ester

(3S,3aS,7aR)-3-Formyl-2-(4-methoxy-benzyl)-3a,5,5-trimethyl-1-oxo-octahydro-4-oxa-2-aza-5-sila-indene-3-carboxylic acid methyl ester