To a solution of 4-[5-(chloromethyl)-1H-tetrazol-1-yl]-2-(trifluoromethyl)benzonitrile (Intermediate 24, 575 mg, 2.00 mmol) in acetonitrile (10 mL) was added triethylamine (0.558 mL, 4.00 mmol) and 1,1-dimethylethyl 1-piperazinecarboxylate (410 mg, 2.20 mmol). The mixture was then heated to 120° C. for 20 min in a microwave reactor. The crude product was purified by silica chromatography (Biotage SP4, 40+S), eluting with 30% ethyl acetate in hexane (2 column volumes) then a gradient from 30-60% ethyl acetate in hexane (10 CV) then 60% ethyl acetate in hexane (2 column volumes). The relevant fractions were evaporated under vacuum to leave a white solid, 1,1-dimethylethyl 4-({1-[4-cyano-3-(trifluoromethyl)phenyl]-1H-tetrazol-5-yl}methyl)-1-piperazinecarboxylate (532 mg).
