3,3-difluoro-6-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1,6-diaza-spiro[3.5]nonane-1-carboxylic acid benzyl ester → 4-(3,3-difluoro-1,6-diaza-spiro[3.5]non-6-yl)-7H-pyrrolo[2,3-d]pyrimidine

To a solution of an optically-active compound of 3,3-difluoro-6-(7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1,6-diaza-spiro[3.5]nonane-1-carboxylic acid benzyl ester (12.0 g) in methanol/tetrahydrofuran (120 ml/120 ml) was added 10% palladium carbon (2.4 g), and the mixture was hydrogenated at room temperature under 4 atmospheres for 21 hours. The mixture was filtered through Celite, and the filtrate was concentrated under reduced pressure. The resulting residue was slurry-purified by a mixed solvent of n-hexane/ethyl acetate (2/1) to give the titled compound (6.6 g).