Synthesis Methodologies Of N-Heterocycles And Spirocyclic Indene Compounds

N-containing heterocyclic compounds are ubiquitous in natural products and pharmacologically active molecules,which exhibit useful behavior in the fields of biology,medicine,pesticides,and materials research.Particularly,five-and six-membered N-heterocycles(thiazoles,thiazolones and azepine compounds)are widely present in various biologically active molecules and play an important role in the development of innovative drugs.On the other hand,spirocyclic indenes,as spiro compound with special structure,are also often found in natural products and pharmacologically active molecules.In recent years,more and more organic chemists construct various heterocyclic compounds under metal-free and green conditions due to the concept of"green chemistry".It is still an important research task in the field of organic synthesis to develop green,environmentally friendly,simple and efficient strategies to synthesize various novel compounds.This dissertation mainly illustrated the synthesis methods of thiazol-2-one,1,4,2-dithiazole and 1-benzazepine through simple substrates such as 1,3-diketone,KSCN,and phenyl isothiocyanate under eeco-friendly reaction conditions.And the1-phenylcyclobutanol was carried out to synthesize a spirocyclic indene compound,which is a kind of all-carbon spirocyclic compounds.The main research contents are as follows:1.An efficient I₂-promoted strategy has been developed for the synthesis of thiazol-2(3H)-one derivatives from 1,3-diketones with potassium thiocyanate.This[3+2]cyclization reaction involves C-S,C-N,and C=O bond formation and exhibits good functional group tolerance.A series of thiazol-2(3H)-one derivatives are obtained in moderate to good yields.2.A catalyst-free method for the preparation of 1,4,2-dithiazoles is developed by reactions of isothiocyanates with hydroxylamine triflic acid salts.The reactions proceed only in hexafluoroisopropanol(HFIP)under room temperature.This synthetic strategy provides new ideas for the application of Hydroxylamine triflic acid salts and the construction of 1,4,2-dithiazole compounds.3.A metal-free approach for the synthesis of seven-membered N-heterocycles has been developed by the I₂-promoted intramolecular electrophilic cyclization.In this reaction,A series of benzo[b]azepine derivatives are obtained intramolecular annulation of butenyl anilines.The features of this reaction are metal-and additive-free,simple operation,and atom economy.The synthesis of this benzazepine derivative enriches the types of seven-membered nitrogen heterocyclic compounds and provides new possibilities for exploring heterocyclic compounds with medicinal value.4.The acid-catalyzed[3+2]spiroannulation reaction the synthesis of spiro[cyclobuta[a]indene-7,1'-cyclobutane]derivatives with unique structures.This TFA-Catalyzed reaction proceeds at room temperature,and fetures oxidants and additives free.We propose a reasonable reaction mechanism for this reaction.In this reaction,1-phenylcyclobutanol is converted to carbocation intermediate through acid catalysis,which undergoes Friedel-Crafts alkylation to obtain the final product.