The Study Of C-C And C-N Bond Formation Reactions Catalyzed By Bronsted Acids

The construction of C-C bonds and C-N bonds is one of the most important areas in modern organic chemistry. The traditional methods to achieve these transformations usually need expensive metal catalysts or tedious steps, which are against the demands of enviromental benignity and atom economy in "green chemistry". In this thesis, we report our investigations of C-C and C-N bond formation reactions with Br(?)nsted acids as the catalysts. This thesis consists of four parts.Part 1:The microwave-assisted addition ofβ-dicarbonyl compounds to secondary alcohols has been achieved efficiently for the first time, using very cheap fluoroboric acid as the catalyst. For various P-dicarbonyl compounds and a series of secondary alcohols, the direct additions give high yields only after 5 minutes of microwave irradiation.Part 2:Under the conventional heating condition or the microwave-assisted condition, the reactions ofβ-dicarbonyl compounds and alcohols with sulfuric acid as the catalysts demonstrated similar reaction results. For various P-dicarbonyl compounds and a series of alcohols, the catalystic reactions under conventional thermal condition and microwave irradiation condition all gave high yields only after 5 minutes.Part 3:The new silica gel supported triflic acid was readily prepared via simple absorption of TfOH onto silica gel. This solid acid was applied as an efficient catalyst for the heterogeneous addition of variousβ-dicarbonyl compounds to a series of alcohols and alkenes, which afforded good to excellent yields under solvent-free conditions or in nitromethane. Moreover, this silica gel supported catalyst can be readily recovered and reused up to 5 runs with almost maintained reactivity and yields.Part 4:In the hydroamination of alkene with sulfonamide, the readily recovery and efficient reusability of the catalyst, triflic acid, have been achieved successfully through simply adding wet silica gel as the adsorbent. This silica gel absorbed TfOH can be readily recovered and reused up to 5 runs with almost maintained reactivity and yields. Moreover, for a series of alkenes and various sulfonamides, the hydroaminations catalyzed by this silica gel absorbed TfOH afforded moderate to excellent yields.