4-Toluenesulfonyl chloride → N-(2,5-difluorophenyl)-4-methylbenzenesulfonamide

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Reaction Steps

Following Intermediate Method 1, a substituted aniline, for example 2,5-difluoroaniline, may be reacted with 4-methylphenylsulfonyl chloride in pyridine to form N-(4-methylphenylsulfonyl)-2,5-difluoroaniline, (V). Nitration of (V) with sodium nitrite in nitric acid, acetic acid and water produces N-(4-methylphenylsulfonyl)-2,5-difluoro-4-nitroaniline, (VI). The reaction of (VI) with aqueous sulfuric acid yields 2,5-difluoro-4-nitroaniline, (VII). Subsequent reaction of (VII) with acetic anhydride and a small amount of dimethylaminopyridine (DMAP) in methylene chloride produces N-(2,5-difluoro-4-nitrophenyl)-acetamide (VIII). Treatment of (VIII) with a borane/dimethyl sulfide complex in tetrahydrofuran yields N-ethyl-2,5-difluoro-4-nitroaniline, (IX). Repeating the previous two steps, the reaction of (IX) first with acetic anhydride (to produce N-(2,5-difluoro-4-nitrophenyl)-acetamide, (X)) followed by treatment with a borane/dimethyl sulfide complex yields N,N-diethyl-2,5-difluoro-4-nitroaniline, (XI). Hydrogenation of (XI) with platinum oxide in ethanol produces the desired 2,5-difluoro-4-diethylaminoaniline, (XII). ##STR28##

Provenance & Evidence