DIPEA (0.21 mL, 1.2 mmol) was added to a solution of 2-bromo-1-(6-bromoquinolin-2-yl)ethanone (268 mg, 0.815 mmol)) and (1R,3S,5R)-2-(tert-butoxycarbonyl)-2-azabicyclo[3.1.0]hexane-3-carboxylic acid (204 mg, 0.896 mmol) in acetonitrile (8 mL) and the reaction mixture was stirred at rt for 16 h. The reaction mixture was diluted with sat. aq. NaHCO3 (5 mL) and extracted with EtOAc (2×20 mL). The combined organic layers were washed with brine, dried (MgSO4), filtered and concentrated. The crude product was purified by flash silica gel chromatography (used DCM as loading solvent, eluted with Et2O/hexanes, gradient from 10% to 30% Et2O) to yield (1R,3S,5R)-3-(2-(6-bromoquinolin-2-yl)-2-oxoethyl) 2-tert-butyl 2-azabicyclo[3.1.0]hexane-2,3-dicarboxylate (332 mg) as white solid. LC-MS retention time 4.283 min; m/z 476.88 (MH+). LC data was recorded on a Shimadzu LC-10AS liquid chromatograph equipped with a PHENOMENEX® Luna 3u C18 2.0×50 mm column using a SPD-10AV UV-Vis detector at a detector wave length of 220 nM. The elution conditions employed a flow rate of 0.8 mL/min, a gradient of 100% Solvent A/0% Solvent B to 0% Solvent A/100% Solvent B, a gradient time of 4 min, a hold time of 1 min, and an analysis time of 5 min where Solvent A was 10% MeOH/90% H2O/0.1% trifluoroacetic acid and Solvent B was 10% H2O/90% MeOH/0.1% trifluoroacetic acid. MS data was determined using a MICROMASS® Platform for LC in electrospray mode.
