p-Toluenesulfonic acid → 5-Benzyloxycarbonylamino-2-pyrrolidone

Participants

Reaction Steps

WO 93/09120 describes a process for the preparation of dimiracetam (2,5-dioxohexa-hydro-1H-pyrrolo[1,2-a]imidazole) 1 and related compounds. 5-Ethoxy-2-pyrrolidone is reacted with benzyl carbamate with a catalytic amount of p-toluenesulfonic acid to give 5-benzyloxycarbonylamino-2-pyrrolidone. This compound is then deprotonated at the pyrrolidine nitrogen with sodium hydride in acetonitrile, and reacted with ethyl bromoacetate to give ethyl 5-benzyloxycarbonylamino-2-oxo-1-pyrrolidine-acetate 2. Cyclization can then be performed after cleavage of the ethyl ester and/or the benzyloxycarbonyl protecting group in the presence of a variety of cyclizing agents.

Provenance & Evidence