To a solution of 5-methyl-2-trityl-2H-tetrazole (68.5 mg, 0.21 mmol) in tetrahydrofuran (THF) (1 mL) stirred under nitrogen at −70° C., was added a solution of n-BuLi (1.6 M in hexanes, 0.144 mL, 0.231 mmol) and tetrahydrofuran (THF) (1 mL) dropwise over 1 minute. The reaction mixture was stirred at −78° C. for 45 minutes, then 4-acetyl-N-(2,4-dimethylphenyl)-N-isobutylbenzenesulfonamide (106 mg, 0.294 mmol) in tetrahydrofuran (THF) (1 mL) was added dropwise at −78° C. over 1 minute. The reaction mixture was stirred at −78° C. for 1 hour, then allowed to warm to room temperature. The reaction was carefully quenched using a few drops of water under nitrogen. Ethyl acetate (3 mL) and water (2 mL) were then added and the reaction stirred vigorously for 5 minutes. The organic phase was separated using a hydrophilic frit and concentrated in vacuo to give a residue. LCMS analysis showed incomplete reaction, so the above reaction procedure repeated using fresh n-butyl lithium solution and reintroducing the crude residue instead of new starting material, this resulted in improved conversion. The residue was then purified by flash silica (Si) chromatography (using a 0-25% ethyl acetate-cyclohexane gradient) to give the required product (22 mg) as a colourless gum. LCMS (M+1) 686, RT 1.57 mins.
