1.68 g (S)-5-biphenyl-4-ylmethyl-1-(2,2-dimethylpropionyl)pyrrolidin-2-one (1, R1=pivaloyl) is added to 10 ml toluene. The mixture is then cooled to −15° C. 5.5 ml Lithium bis(trimethylsilyl)amide (1 M in THF) is then added. After 1 h, a mixture of 1.3 g phenyl selenyl bromide in 10 ml toluene is added. After a further 30 min, 100 ml water is added. The phases are separated and the organic phase concentrated in vacuo. The residue is taken up in 25 ml ethyl acetate and then 5.1 ml hydrogen peroxide (37%) is added at room temperature. After 1 h, the phases are separated and the organic phase washed with a saturated sodium hydrogen carbonate solution and then dried (MgSO4). The mixture is concentrated in vacuo and purified by column chromatography, eluting with heptane/ethyl acetate 5:1 to afford (R)-5-Biphenyl-4-ylmethyl-1-(2,2-dimethylpropionyl)-1,5-dihydropyrrol-2-one. 1H NMR (CDCl3): 1.28 (9H), 2.70 (1H), 3.30 (1H), 4.97 (1H), 5.89 (1H), 7.06 (2H), 7.19 (2H), 7.31 (2H), 7.41 (4H).
