1,1'-Carbonyldiimidazole → (4s)-4-Benzyl-3-[(8-bromo-6-fluoro-2,3-dihydro-1h-pyrrolo[1,2-a]indol-1-yl)acetyl]-1,3-oxazolidin-2-one

Participants

Reaction Conditions

Reaction Steps

To a solution (S)-(−)-4-benzyl-2-oxazolidinone (7.8 g, 43.8 mmol) in THF (300 mL) at −78° C. was slowly added 1.6M n-butyllithium (27.3 mL, 43.8 mmol). The mixture was stirred for 30 minutes at −78° C. and a mixture of the compound of Step 1 (10.5 g, 33.7 mmol) and 1,1′-carbonyldiimidazole (6 g, 37 mmol) in THF (100 mL) was added. The mixture was stirred for 30 minutes at −78° C. and then warmed to −30° C. and stirred for 2 hours. The reaction was quenched with saturated NH4Cl, the phases were separated and the aqueous layer was extracted with EtOAc. The combined organic layers were washed with brine, dried over Na2SO4 and concentrated. The residue was purified by silica gel chromatography eluted with 10% EtOAc in Toluene, which permitted the separation of the two diastereomers. Both isomers were obtained as an yellow solid with diastereomeric excess >95%.

Provenance & Evidence