| The N,N’-dimethylaminopyridine (DMAP) was first successfully used as one oforganocatalysts in acetyl transfer reactions with remarkable efficiency. Since1996, many kindsof chiral DMAP derivatives have been explored and successfully applied in various kinds ofacetyl transfer reactions. Various kinds of DMAP derivatives with chiral centre, chrial axis andchrial plane have been explored. The design and synthesis of these compounds has become oneof the frontier fields in organic synthesis.In this thesis, the properties of pyridine, the chiral DMAP catalysts and the synthesis oftetraphenylene and its derivatives are reviewed in brief. Then, a novel class of DMAP derivativeshas been designed based on the saddle shape skeleton of cyclooctatetraene, which has beendivided into several building blocks of bipyridinyl and biphenyl by retro-synthetic analysis. Thesynthesis of these building blocks have also been discussed. Based on the building blocksobtained, the construction of the cyclooctatetraene skeleton has been attempted. The mainprogresses are summarized as the follows.(1)3-Hydroxy-2-nitropyridine has been obtained from3-hydroxypyridine through nitration.However, the cholorination of this compound to3-chloro-2-nitropyridine was failed, and thefurther investigation has to be halted.(2)3,3’-Dibromo-2,2’-bipyridine has been prepared successfully from commerciallyavailable3-amino-2-chloropyridine through amino protection, Ullmann coupling, deprotectionand Sandmeyer reaction successively. The total yield of these four steps is around20%, layingthe experimental foundation of the construction of the cyclooctatetraene skeleton.(3)4-Amino-2-halo-3-nitropyridine has been prepared successfully from availablecommercially2,4-dihydroxy-3-nitropyridine through selective cholorination and aminosubstitution. Then, the derivatives of2,2’-bipyridine have been prepared successfully from thesecompounds through Ullmann coupling and reduction of nitro group. The total yields of thesefour steps are about20. Some attempts have been made to synthesize3,3’-dibromo-4,4’-diamino-2,2’-bipyridine through Sandmeyer reaction but got failed.(4)2,2’-Dimethoxy-6,6’-diiodobiphenyl has been prepared successfully from available3-nitrophenol through iodination, methylation, Ullmann coupling, reduction of nitro group andSandmeyer reaction. The total yield of these five steps is about20%.1,8,9,16-Tetramethoxytetraphenylene has been obtained from2,2’-Dimethoxy-6,6’-diiodobiph-enyl by n-BuLi/CuCl2coupling with the yield of28%.(5) Some preliminary attempts have also been made to synthesize tetrapyridine by n-BuLi/CuCl2coupling but got failed.In this thesis,40multi-substituted pyridine and benzene derivatives, including17unknownpyridine derivatives, have been synthesized successfully. All the compounds obtained have beencharacterized by IR,1H NMR,13C NMR, MS and HRMS. Although the target tetrapyridinederivatives has not been obtained, the synthetic methodology has been investigatedsystematically and a series of important bipyridine and biphenyl derivatives have beensynthesized successfully, making a solid foundation for further research. |
