合成路线1

The intermediate fluoropyrrolidine (XIV) was obtained as follows: Alkylation of ethyl acetoacetate (I) with 1,2-dibromoethane (II) led to the cyclopropane derivative (III). Bromination of (III) provided bromo ketone (IV), which was condensed with (S)-1-phenylethylamine (V), yielding amino ketone (VI). Acylation of amine (VI) with (diethylfosfonyl)fluoroacetyl chloride (VII) gave amide (VIII). Intramolecular Wadsworth-Emmons condensation of keto phosphonate (VIII) in the presence of potassium tert-butoxide produced the pyrrolinone (IX). Catalytic hydrogenation of the pyrroline double bond of (IX), followed by separation of the resultant diastereomeric mixture, furnished pyrrolidinone (X). After saponification of the ethyl ester group of (X), the resulting acid (XI) was subjected to Curtius rearrangement in the presence of DPPA and t-BuOH, giving rise to carbamate (XII). Lactam (XII) reduction by means of borane in THF afforded pyrrolidine (XIII). The N-phenylethyl group of (XIII) was then removed by hydrogenation over Pd/C to furnish the required intermediate pyrrolidine (XIV) (See scheme no. 27170201a, intermediate (IX)).