A mixture of [2-(4-nitrophenyl)-1-(S)-thiocarbamoylethyl]-carbamic acid tert-butyl ester, 2, (0.343 g, 1.05 mmol), 2-bromo-acetophenone (0.231 g, 1.15 mmol), in CH3CN (5 mL) is refluxed 1.5 hour. The solvent is removed under reduced pressure and the residue re-dissolved in CH2Cl2 then pyridine (0.24 mL, 3.0 mmol) and Boc2O (0.24 mL, 1.1 mmol) are added. The reaction is stirred for 2 hours and diethyl ether is added to the solution and the precipitate which forms is removed by filtration. The organic layer is dried (Na2SO4), filtered, and concentrated to a residue which is purified over silica to afford 0.176 g (39%) of the desired product ESI+MS 426 (M+1).
