C(Cl)(=O)C(Cl)=O.[Br:7][C:8]1[CH:13]=[CH:12][C:11]([CH2:14][CH2:15][C:16]([CH3:24])([S:20]([CH3:23])(=[O:22])=[O:21])[C:17](O)=[O:18])=[CH:10][CH:9]=1.CN(C=O)C.[Si]([O:34][NH2:35])(C)(C)C>C(Cl)Cl>[Br:7][C:8]1[CH:13]=[CH:12][C:11]([CH2:14][CH2:15][C:16]([CH3:24])([S:20]([CH3:23])(=[O:22])=[O:21])[C:17]([NH:35][OH:34])=[O:18])=[CH:10][CH:9]=1
Oxalyl chloride (4.50 mL, 50 mmol) was added to a solution of 4-(4-bromophenyl)-2-methyl-2-(methylsulfonyl)butanoic acid (II) (14.69 g, 43.82 mmol) in DCM (300 mL) under nitrogen at ambient temperature, followed by DMF (340 ul). The reaction was stirred until effervescence ceased and then was allowed to stir for 1 hour. O-TMS-hydroxylamine (16.0 mL, 130 mmol) was added via syringe and the suspension was stirred for 1 hour. The reaction was quenched with methanol (60 mL), stirred for 1 hour and concentrated in vacuo to afford a yellow-white solid. The solid was triturated in DCM (200 mL) overnight. The solid was collected by filtration, washed with 1:1 DCM:heptane (2×100 mL), and dried under vacuum to afford the title compound as a white solid (14.85 g, 96.76%). LC-MS m/z 350.0 (M+1). 1H NMR (500 MHz, METHANOL-d4) δ ppm 1.64 (s, 3H) 2.00-2.10 (m, 1H) 2.44-2.58 (m, 2H) 2.61-2.77 (m, 1H) 3.04 (s, 3H) 7.18 (d, J=8.29 Hz, 2H) 7.44 (d, J=8.29 Hz, 2H).
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