Water → 1-(Phenylmethyl) (2S,4R)-4-hydroxy-1,2-pyrrolidinedicarboxylate

Participants

Reaction Steps

A solution of benzyl chloroformate (50 mL, 0.35 mol) in Et2O (160 mL) was added dropwise, during 10 min, to a rapidly stirred mixture of trans-4-hydroxy-L-proline (39.8 g, 0.308 mol), NaHCO3 (63.7 g, 0.758 mol) and H2O (660 mL). The reaction mixture was stirred at room temperature for 20 h. The layers were separated, and the aqueous layer was washed with Et2O (4×200 mL), cooled, and then acidified to pH 1-2 with concentrated hydrochloric acid The resulting emulsion was extracted with EtOAc (5×200 mL). Combined EtOAc extracts were washed in succession with H2O (3×500 mL) and brine (3×500 mL), dried over MgSO4, and then concentrated in vacuo to give intermediate (4) as a colorless foam (62.7 g, 78%). Additional reactions were carried out to give a total of 284 g of product suitable for further transformation.

Provenance & Evidence