Add 1-(2-(4-(6-methoxy-2-(5-(methylthio)thiophen-2-yl)naphthalen-1-yloxy)phenoxy)ethyl)piperidine (84 mg, 0.17 mmol), tetrahydrofuran (3.3 mL) and methanol (3.3 mL) to a round bottom flask under nitrogen. Cool the resulting solution to 0° C. and add solution of potassium peroxymonosulfate sulfate (102 mg; 0.17 mmol) in water (1.7 mL). Stir the resulting mixture at 0° C. for 30 min. Load the mixture onto an SCX acidic ion exchange column. Flush the column with 1:1 methanol/dichloromethane and elute with 1:1 2M ammonia in methanol/dichloromethane. Concentrate the ammonia containing eluent in vacuo to give the title compound (87 mg, 0.17 mmol): mass spectrum (m/z): 522 (M+1).
