Into the solution of {3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]azetidin-3-yl}acetonitrile dihydrochloride (2.6 g, 6.3 mmol), tert-butyl 4-oxo-1-piperidinecarboxylate (1.3 g, 6.3 mmol) in THF (30 mL) were added N,N-diisopropylethylamine (4.4 mL, 25 mmol) and sodium triacetoxyborohydride (2.2 g, 10 mmol). The mixture was stirred at room temperature overnight. After adding 20 mL of brine, the solution was extracted with EtOAc. The extract was dried over anhydrous Na2SO4 and concentrated. The residue was purified by combiflash column eluting with 30-80% EtOAc in hexanes to give the desired product, tert-butyl 4-{3-(cyanomethyl)-3-[4-(7-{[2-(trimethylsilyl)ethoxy]methyl}-7H-pyrrolo[2,3-d]pyrimidin-4-yl)-1H-pyrazol-1-yl]azetidin-1-yl}piperidine-1-carboxylate. Yield: 3.2 g (86%); LC-MS: [M+H]+=593.3.
