A suspension of 7-(4-bromo-2,6-dimethyl-phenyl)-4-chloro-2,5,6-trimethyl-7H-pyrrolo[2,3-d]pyrimidine (2.0 g), 3-(piperidin-4-yl)propionitrile (1.4 g) and N,N-diisopropylethylamine (1.4 g) in EtOH (4 mL) was heated at 100° C. in a sealed tube for 11 hours. After cooling to room temperature, the solvent was removed under reduced pressure. The residue was purified with column chromatography (silica gel: Wako gel C200, eluent: hexane:ethyl acetate:CHCl3=8/2/1) to obtain 3-{1-[7-(4-bromo-2,6-dimethyl-phenyl)-2,5,6-trimethyl-7H-pyrrolo[2,3-d]pyrimidin-4-yl]-piperidin-4-yl}-propionitrile (2.0 g) as a white crystal.
