(S)-1-{(3S,3aS,7S,7aR)-octahydro-7-hydroxy-3a-methyl-1H-indene-3-yl}ethyl formate → (S)-1-{(3S,3aR,7aR)-octahydro-3a-methyl-7-oxo-1H-indene-3-yl}ethyl formate

Under a nitrogen atmosphere, a solution of (S)-1-{(3S,3aS,7S,7aR)-octahydro-7-hydroxy-3a-methyl-1H-indene-3-yl}ethyl formate (Compound 16: 899.6 mg, 3.975 mmol) in acetonitrile (10 ml) was cooled in an ice bath, and tetra-n-propylammonium perruthenate (35 mg, 0.0994 mmol) was added thereto. The reaction mixture was stirred in the ice bath for 3 minutes, and at room temperature (23° C.) for 45 minutes. The reaction mixture was filtered through Celite, and the resulting mixture was washed with ethyl acetate, followed by evaporation under reduced pressure. The crude product was purified by flash column chromatography to obtain (S)-1-{(3S,3aR,7aR)-octahydro-3a-methyl-7-oxo-1H-indene-3-yl}ethyl formate (865.1 mg).