反应详情

温度

57 °C

To 2.00 g (7.16 mmol) of (2S,4R)-4-Hydroxy-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester in 20 mL of acetone was added 5.64 g of silver oxide (24.3 mmol) and 1.56 mL of iodomethane (25.0 mmol) and the mixture was stirred at 57° C. for 28 h. The solution was cooled to 25° C., filtered through celite and concentrated. Purification was through 50 mL of silica by eluting with EtOAc:Hexane (8:1) and the purified fractions were concentrated to give a 2.0 g (96%) of (2S,4R)-4-Methoxy-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester as a clear oil. HPLC: Rt 3.79 min. (100% area). 1H NMR (CDCl3, 400 MHz) δ: 7.31-7.23 (5H, m), 5.22-5.00 (2H, m), 4.44-4.40 (1H, m), 4.10-4.02 (1H, m), 3.76 (3H, s), 3.69-3.60 (1H, m), 3.54 (2H, s), 3.29 (3H, bs), 2.42-2.30 (1H, m). LCMS (ESI) (M+Na+) m/z: 316.1.

1. temperatureThe solution was cooled to 25° C.
2. filtrationfiltered through celite and
3. concentrationconcentrated
4. customPurification
5. washby eluting with EtOAc:Hexane (8:1)
6. concentrationthe purified fractions were concentrated