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The tetrazole (27.3 g, 104 mmol) from Step (a) was treated with 4-bromomethyl-benzoic acid tert-butyl ester (31.0 g, 114 mmol) and cesium carbonate (74.3 g, 228 mmol) in dimethylformamide (400 mL) at room temperature for 5.5 hours. The solvent was evaporated in vacuo and the residue passed through a pad of silica gel eluting with CH2Cl2:THF 19:1, to give a 9:1 mixture of regioisomers (40.07 g, 93%). 1H NMR (DMSO-d6) δ 9.16 (s, 1H), 8.87 (s, 1H), 8.54 (s, 1H), 7.91 (d, J=8 Hz, 2H), 7.51 (d, J=9 Hz, 2H), 6.13 (s, 2H), 1.57 (s, 9H).

1. customThe solvent was evaporated in vacuo
2. customto give
3. additiona 9:1 mixture of regioisomers (40.07 g, 93%)