Synthesis Of Aromatic Heterocycles Via Enaminone Participated Aromatic Annulation

Aromatic heterocycles constitute a class of organic compounds with huge amount,and they are widespread used in medicines,agriculture and photoelectric materials.The aromatic annulation reactions are one of the major tools to access aromatic heterocycles,they are thus valuable for the advance of aromatic chemistry.This thesis focus on the heteroaromatic compound synthesis via enaminone participated annulation reactions.Three different sections of research works are included.The first section is the metal-free synthesis of 5-thio-1,2,3-triazoles in water medium.By means of the[3+2]annulation of N,S-ketene acetals?alkyl thiolated enaminones?and tosyl azide,we realized the first synthesis of 5-thiolated1,2,3-triazoles under metal-free condition.The reactions have been run in water medium in the presence of TMEDA,providing a green synthetic method toward1,2,3-triazoles functionalized with sulfur side chain.The second section is the synthesis of N-heterocycle fused 1,2,3-triazoles with heterocyclic enaminones.With the[3+2]annulation reactions of heterocyclic enaminones and tosyl azide,the N-heterocycle fused 1,2,3-triazoles have been synthesized.Besides various N-heterocyclic enaminones,the N,N-ketene acetals are also tolerated.The results provide new route to the synthesis of fused 1,2,3-triazoles and nitrogen side chain functionalized 1,2,3-triazoles.The third section is the synthesis of isothiazoles via enaminone participated annulation using enaminones and thiuram.By employing primary enaminones and tetramethyl thiuram as starting materials,the full substituted isothiazoles have been synthesized in the presence of I₂/TBHP.Comparing with conventional methods,this method proceeds via Newman-Kwart rearrangement,disclosing new synthetic applications of enaminones.