A mixture of Pd(OAc)2 (90 mg, 0.42 mmol) and 1,1'-bis(diphenylphosphino)ferrocene (300 mg, 0.56 mmol) in DMF (40 mL) was heated at 90° C. for 15 minutes while argon was being passed through the mixture. After cooling the burgundy solution to ambient temperature, 5-[(4-bromophenyl)methyl]-2-(1,1-dimethylethyl)-2H-tetrazole (4.0 g, 14 mmol), t-butyl acrylate (3.1 g, 23 mmol) and triethylamine (2.8 mL, 20 mmol) were added to the mixture. The reaction was heated at 90° C. overnite and then concentrated. After filtering the dark mixture through a short column of silica gel using a mixture of hexanes and ethyl acetate (4:1), the fractions containing product were pooled and concentrated. Final purification was achieved by chromatography on a Waters Prep 500 liquid chromatograph fitted with two silica gel cartridges eluting with a mixture of hexanes and ethyl acetate (9:1) to give pure 1,1-dimethylethyl 4-[[2-(1,1-dimethylethyl)-2H-tetrazol-5-yl]methyl]benzene propenoate (3.9 g, 11.3 mmol) in 81% yield. The analytical sample was recrystallized from ethyl acetate and hexanes, mp. 105°-106° C.
