2-Benzyl 1-tert-butyl (2S)-5-oxopyrrolidine-1,2-dicarboxylate → 2-Tert-butoxycarbonylamino-5-(3,4-dimethoxy-phenyl)-5-oxo-pentanoic acid benzyl ester

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Reaction Steps

A solution of (2S)5-oxo-pyrrolidine-1,2-dicarboxylic acid 2-benzyl ester 1-tert-butyl ester (8.20 g, 0.026 mol, 1.0 equivalent) in anhydrous THF was cooled to 0° C. in an ice bath under N2. A chilled 0.5M solution of 3,4-dimethoxyphenylmagnesium bromide in THF (52.1 mL, 0.026 mol, 1.0 equivalent) was slowly added. The reaction mixture was allowed to stir for two hours. The reaction was quenched upon addition of saturated NH4Cl solution (10 ml). The mixture was partitioned between ethyl acetate and brine. The organic extract was washed with brine (3×100 ml). The ethyl acetate layer was dried over anhydrous Na2SO4 and concentrated in vacuo. The resulting crude blue oil was filtered through a layer of silica. The filtrate was concentrated in vacuo to afford 2-tert-butoxycarbonylamino-5-(3,4-dimethoxy-phenyl)-5-oxo-pentanoic acid benzyl ester (10.46 g, 0.023 mol, 88% yield). Analysis H1 NMR (400 MHz, CDCl3): 7.5–7.3 (6H, m), 7.0–6.7 (2H, m), 5.2 (2H, m), 4.0–3.8 (6H, m), 3.0 (1H, m), 2.6–1.9 (4H, m), 1.4 (9H, s). MS (LC-MS): Calculated for C25H31NO7 457.21, found 458.19 (M+H)+.

Provenance & Evidence