[CH3:1][C:2]1[N:3]=[N:4][N:5]([C:7]([C:20]2[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=2)([C:14]2[CH:19]=[CH:18][CH:17]=[CH:16][CH:15]=2)[C:8]2[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=2)[N:6]=1.[Li]CCCC.[C:31]([C:34]1[CH:39]=[CH:38][C:37]([S:40]([N:43]([C:48]2[CH:53]=[CH:52][C:51]([CH3:54])=[CH:50][C:49]=2[CH3:55])[CH2:44][CH:45]([CH3:47])[CH3:46])(=[O:42])=[O:41])=[CH:36][CH:35]=1)(=[O:33])[CH3:32]>O1CCCC1>[CH3:55][C:49]1[CH:50]=[C:51]([CH3:54])[CH:52]=[CH:53][C:48]=1[N:43]([CH2:44][CH:45]([CH3:47])[CH3:46])[S:40]([C:37]1[CH:38]=[CH:39][C:34]([C:31]([OH:33])([CH3:32])[CH2:1][C:2]2[N:3]=[N:4][N:5]([C:7]([C:8]3[CH:13]=[CH:12][CH:11]=[CH:10][CH:9]=3)([C:14]3[CH:15]=[CH:16][CH:17]=[CH:18][CH:19]=3)[C:20]3[CH:25]=[CH:24][CH:23]=[CH:22][CH:21]=3)[N:6]=2)=[CH:35][CH:36]=1)(=[O:42])=[O:41]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.
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