*3.5. Synthesis of Papaverine* N*-oxide DiversinateTM Analogue (13)*

Papaverine *N*-oxide (**12**, 35.5 mg, 0.1 mmol) was dissolved in CH2Cl2/H2O (2.5:1, 100 μL:40 μL) before the addition of (CF3SO2)2Zn (198.9 mg, 0.6 mmol) at room temperature. The mixture was cooled to 0 ◦C before TBHP (40 μL, 0.6 mmol) was slowly added, after which time, the stirred mixture slowly warmed to room temperature over 16 h. The crude reaction product was dried under N2 and pre-adsorbed to C18-bonded silica (≈1 g) overnight with the dry material packed into a stainless-steel guard cartridge, which was subsequently attached to a C18 semi-preparative HPLC column. Isocratic conditions of H2O/MeOH/TFA (90:10:0.1) were run for the first 10 min, followed by a linear gradient of MeOH/TFA (100:0.1) over 40 min, then isocratic conditions of MeOH/TFA (100:0.1) for a further 10 min, all at a flow rate of 9 mL/min. Sixty fractions (60 × 1 min) were collected from the start of

the HPLC run. Fractions containing UV-active material were analyzed using 1H NMR spectroscopy and LCMS in order to identify products of interest. The starting material (**12**, 9.3 mg, 26%) eluted in fraction 39, while a mixture (<80% pure) containing predominantly the mono-CF3 papaverine *N*-oxide analogue (**13**, 5.1 mg, <12%) eluted in fraction 43. While 1H NMR and LCMS analysis of the fraction 43 mixture indicated product **13** had been made, the paucity of material and low yield, meant no further purification or characterization was undertaken.
