Dissolve (S)-1,4-dibenzyl-2-vinylpiperazine (16.2 g, 55.5 mmol) in tetrahydrofuran (370 mL), add 9-BBN (0.56 L of a 0.5 M solution in tetrahydrofuran) via addition funnel, stir at room temperature overnight. Cool to 0° C. and treat with 30% aqueous hydrogen peroxide (195 mL), followed by 3N aqueous sodium hydroxide (195 mL). Allow to reach room temperature and stir for 24 h. Pour into separatory funnel, separate organic layer and remove solvent in vacuo. Take up residue in dichloromethane, add water and recombine with aqueous layer from before. Pour into separatory funnel, separate organic layer and extract aqueous layer with several portions of dichloromethane. Combine all organic layers, remove solvent in vacuo. Take up residue in 1 L of methanol, add 185 g of SCX resin. Filter slurry through Büchner funnel, washing well with methanol. To elute product, wash cake thoroughly with 50% 7N ammonia-methanol in dichloromethane. Concentrate filtrate in vacuo to obtain the title compound (16.6 g, 96%) as a thick brownish oil: mass spectrum (APCI): m/z=311.2 (M+1).
