[F-:1].[K+].[Br:3][C:4]1[CH:9]=[C:8]([N+:10]([O-:12])=[O:11])[CH:7]=[CH:6][C:5]=1[N:13]=[C:14]=[O:15].[F:16][C:17]([F:24])([F:23])[C:18]([F:22])=[C:19]([F:21])[F:20]>CN(C=O)C>[Br:3][C:4]1[CH:9]=[C:8]([N+:10]([O-:12])=[O:11])[CH:7]=[CH:6][C:5]=1[NH:13][C:14](=[O:15])[C:18]([F:22])([C:19]([F:1])([F:21])[F:20])[C:17]([F:24])([F:23])[F:16]Potassium fluoride (23 grams; 0.4 mole) which was dried by heating strongly with a bunsen burner in a porcelain crucible and subsequently powdered, was added to 200 ml of a DMF solution of 2-bromo-4-nitrophenyl isocyanate (6 grams; 0.025 mole). The mixture was placed in a pressure vessel, purged with a small stream of hexafluoropropene, and heated to 70° C. while adding hexafluoropropene from a pre-weighed supply cylinder at 10-20 psig. A pressure drop occurred as the gas reacted, and the remaining hexafluoropropene was added intermittently until the supply cylinder was empty; heating was continued at 65°-70° C. for 21/2 hours with pressure stabilized at 5 psig. The reaction vessel was then cooled and the solution poured off and extracted with hexane.. The DMF solution was poured into water and filtered. The solid products were taken up in chloroform, dried over sodium sulfate, filtered, evaporated, and chromatographed on silica gel with ethyl acetate/hexane (1:5). The front-running product was collected; H-NMR of this product indicated the desired product The material was then chromatographed on silica gel with gradient elution from 100% hexane to 100% ethyl acetate.
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