Development of New Method for Preparation of Heterocycles Using Reactive Intermediates.

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It is well known that vinyl cations, one of reactive intermediates, are formed by electrophilic addition to acetylenic bonds. We have also found that photolysis and solvolysis of vinyl halides generate vinyl cations. In this study we investigated formation of heterocycles by intramolecular reaction, in which vinyl cations contain heteroatoms such as oxygen and sulfur at the neighboring position to the cationic center. The results indicated the cyclic structure of the resulting cyclic onium ions and the nature of the heteroatom play a significant role in the stability and the isolation. In particular, in the case of sulfur, the spectral data of the isolated cyclic sulphonium ion and the chemical behaviors suggested the sulphurane structure.Vinyl azides obtained by nucleophilic substitution of vinyl halides afford azirines thermally or photochemically, which undergo C-N fission in thermolysis to produce vinyl nitrenes. the electrocyclic reaction of vinyl nitrenes provides 5, 6, and 7-membered heterocycles. Especially, pyrazine derivatives obtained by dimerization of azirines showed the character of liquid crystals and werre applied to chemistry of molecular assembly. Various heterocycle-containing liquid crystals and amphiphilic compounds were prepared. These compounds formed monolayers. The relationship between the behavior and the structure of the monolayers were considered on the empirical and theoretical results. The LB films prepared by this study showed a large SH intensity and were developed to optical materials.