Phosphorus oxychloride → Isopropyl 3-p-fluorobenzoyl-5,6,7,8-tetrahydropyrrolo[1,2-a]pyridine-8-carboxylate

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Reaction Steps

A solution of 758 mg. of N,N-dimethyl-4-fluorobenzamide and 0.44 ml. of phosphorous oxychloride in 50 ml. of 1,2-dichloroethane is refluxed for one hour. To this solution is added a solution of 500 mg. of isopropyl 5,6,7,8-tetrahydropyrrolo[1,2-a]pyridine-8-carboxylate in 10 ml. 1,2-dichloroethane. The reaction mixture is refluxed for 3 hours. A solution of 3.3 g. sodium acetate trihydrate in 9 ml water is added and refluxed for a further 10 hours. The organic phase is separated, washed with saturated sodium chloride solution, dried over sodium sulfate and evaporated to dryness. The residue is purified by preparative t.l.c. using hexane:ethyl acetate (90:10). Crystallization from dichloromethane-hexane yields isopropyl 3-p-fluorobenzoyl-5,6,7,8-tetrahydropyrrolo[1,2-a]pyridine-8-carboxylate (XI, R=H, L=p-F, R2 =iC3H7, n=1), m.p. 92° C.

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