Ethanol → Ethyl 5-oxo-L-prolinate

Participants

Reaction Steps

A suspension of 30.0 g of L-pyroglutamic acid 133 (232 mmol) in 100 ml of anhydrous ethanol was slowly added with 20 ml of SOCl2 (274 mmol, 1.2 eq.) at 0° C. and subsequently stirred for 15 h, and the batch was thawed to room temperature to form a clear solution. For work-up, all volatile components were completely removed under vacuum, the remaining residue was subsequently taken up in 500 ml of ethyl acetate and successively stirred over K2CO3 and MgSO4, each time removing the drying agent by suction. Filtration over a small amount of silica gel and solvent removal under vacuum afforded 36.0 g (230 mmol, 99%) of ester 203 in the form of a slightly yellowish, viscous oil.

Provenance & Evidence