Studies On The Synthesis Of Nitrogen-Containing Heterocycles Catalyzed By Iodine And Tbhp System

A series of N-containing aromatic heterocycles were synthesized by iodine and t-BuOOH as catalytic system, such oxazoles, imidazoles, imidazo[1,5-a]pyridines, and these methodologies were successfully applied in the synthesis of some simple naturally occurring alkaloids. In this thesis, two parts are included. The first part mainly reviews the recent application of molecular iodine in organic synthesis and synthesis of heterocycles, meanwhile, we also simple summarize the development of cross-dehydrogenerative coupling (CDC) reactions in recent years; the second part focuses on the synthesis of N-containing aromatic heterocycles catalyzed by iodine and t-BuOOH.Preparation of N-containing aromatic heterocycles catalyzed by iodine and TBHP1. This chapter mainly described the synthesis of the polysubstituted oxazoles in the presence of iodine and TBHP through utilizing benzyl amine derivatives and1,3-dicarbonyl compounds as the reaction substrates. This reaction process firstly made the polarity1,3-dicarbonyl compounds reversed, then undergoed intermolecular nucleophilic substitution, benzyl oxidation, intramolecular nucleophilic addition and the last oxidation process. In the end, the corresponding product was obtained. This is the first report that polysubstituted oxazoles were directly contructed from two readily available starting materials.2. Based on the result of the above chapter, phenylacetaldehyde chosen as the reaction sustrate reacted with benzylamine, and imidazole compound was obtained through NMR and X-crystallographic analysis. We further optimized the reaction conditions and found that other benzylamine derivatives can also reacted with phenylacetaldehyde to generate the corresponding imidazoles derivatives. Meanwhile, acetophenone derivatives reacted with benzylamine to also obtain the similar imidazoles.3. The synthesis of2,5-disubstituted oxazoles was achieved in the presence of iodine and TBHP from a-aminoketone and aromatic aldehydes on the basis of our previous work. Substrates extension demonstrated that this method was suitable for different substituted aromatic aldehydes. Electronic and steric effect had little influence on the reaction efficiency. We further applied this method in the synthesis of structurally simple alkaloids containing oxazole skeleton, such as texamine, texaline, annuloline etc. A middle to good yield was obtained in the reaction.4. Due to its unique fluorescent character, imidazo[1,5-a]pyridines have already widely applied in organic light-emitting diodes (OLEDs) and in organic thin-layer field effect transistors (FETs). On the basis of our previous work, we choosed pyridin-2-ylmethanamine and aldehydes as the reaction substrates to achieve the synthesis of imidazo[1,5-a]pyridines in the presence of iodine and TBHP. Moreover, a-substituted pyridin-2-ylmethanamine used as substrate reacted with aldehydes to also provide1,3-diarylated imidazo[1,5-a]pyridines. Therefore,3-aryl imidazo[1,5-a]pyridines and1,3-diaryl imidazo[1,5-a]pyridines can be obtained through this method.