Benzyl Bromide → Ethyl 8-(benzyloxy)-2-(4-fluorobenzyl)-1-oxo-1,2,3,4-tetrahydro-pyrrolo[1,2-a]-pyrazine-7-carboxylate

To a solution of ethyl 2-(4-fluorobenzyl)-8-hydroxy-1-oxo-1,2,3,4-tetrahydropyrrolo[1,2-a]-pyrazine-7-carboxylate (8.2 g, 24.6 mmol) in DMF (200 mL), cesium carbonate (10.4 g, 32.0 mmol) and benzyl bromide (3.2 mL, 27.1 mmol) were added. The reaction mixture was stirred at room temperature over night. The mixture was filtered and the filtrate concentrated under vacuum. The residue was partitioned between ethyl acetate and brine. The organic extract was washed with brine, dried over sodium sulfate, filtered, and concentrated under vacuum. The residue was subjected to column chromatography on silica gel eluted with hexanes and ethyl acetate gradient to give titled material.