Benzyl chloroformate → Benzyl 3,3-dimethyl-2-oxopyrrolidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

In an oven-dried 1000 ml flask under argon was dissolved 3,3-dimethyl-2-pyrrolidinone (0.0718 mol, 8.13 g) in 200 ml THF. The resulting solution was cooled to −78° C., and lithium hexamethyldisilazide (0.0790 mol, 79 ml of a 1M solution in THF) was added over 15 min. Stirring was continued for 30 minutes, at which time benzyl chloroformate (0.0790 mol, 13.5 g) was added and the reaction was allowed to warm to room temperature and stir for 16 hr. The mixture was concentrated to ⅓ total volume and diluted with 500 ml ethyl acetate and washed with 1M HCl (2×200 ml), water (1×200 ml), and brine (1×100 ml). The organic phase was dried over MgSO4, filtered and concentrated. Purification of the crude residue on 120 g silica (ethyl acetate/hexanes) yielded 12.3 g (69%) of phenylmethyl 3,3-dimethyl-2-oxo-1-pyrrolidinecarboxylate as a light yellow oil. LCMS (ESI+)=248 m/z (M+), 270 m/z (MNa+). 1H NMR (400 MHz, CDCl3) δ 7.48-7.46 (m, 2H), 7.39-7.36 (m, 3H), 5.31 (s, 2H), 3.77-3.73 (t, 2H, J=6.96 Hz), 1.91-1.88 (t, 2H, J=7.08 Hz), 1.23 (s, 6H). 13C NMR (CDCl3) δ 178.83, 151.86, 135.35, 128.60, 128.34, 128.10, 68.00, 42.79, 42.16, 32.95, 24.28.

Provenance & Evidence