Synthesis Of N,S-Heterocycles Via Multicomponent And Cross-Dehydrogenative Coupling Reactions In Aqueous Media

N,S-heterocycles are ubiquitous in natural products,drug molecules and functional materials.Therefore,developing an efficient and green synthetic method for constructing these compounds always remains highly desirable.In recent years,organic reactions in aqueous media have attracted the much attention.When water is used instead of traditional organic solvents in organic reactions,it has many potential advantages in terms of reaction cost,reaction safety,environmental protection,production efficiency and selectivity.Therefore,the research mainly concetrates on the synthesis of N,S-heterocyclic compounds via efficient and green multi-component reaction and cross-dehydrogenation coupling reaction in aqueous media.The main contents are shown in the following:(1)A one-pot,catalyst-free route to spiro[dihydroquinoline-naphthofuranone]compounds from isatins through ring-opening and cyclization processes in water is disclosed.Hydrogen-bonding effects of water proved to be the key factor to accelerate the transformation.In addition,the chemistry provides several advantages including that it is free of organic solvents,a simple operation,and a gram-scale synthesis and uses inexpensive reagents and a recyclable reaction medium.(2)A one-pot,three-component condensation reaction of 8-quinolinol,2-thiobarbituric acid and isatins or aldehydes in water to give novel barbituroquinoline derivatives is described.The aqueous solution of SDS proves to be an efficient reaction medium for the multicomponent reaction.The reaction is free of catalysts and toxic solvents,operating under mild conditions and allows for ease of product isolation,making it more environmentally friendly.(3)A novel,one-pot,three-component condensation reaction of 2-naphthol,adenine and aliphatic or aromatic aldehydes in aqueous medium to give betti base containing adenine derivatives in the presence of p-toluenesulfonic acid for the first time,is described.As well,we test the inhibitory activity of these compounds on neuraminidase from influenza virus.Meanwhile,betti reaction can be promoted by adding appropriate SDS sufartants in water to form micelles.(4)A metal-free direct thiolation of imidazoheterocycles with various thiophenol in water at room temperature has been developed.Compared with published methods,the chemistry exhibits several advantages including high yields,green solvents and mild condition.The method provides a new route for the construction of C-S bonds of imidazoheterocycles derivatives(5)A metal-free direct sulfenylation of phenol and arylamine derivatives with various heterocyclic thiols and thiones using cross dehydrogenative coupling protocol in water at room temperature has been developed.Reaction conditions involving solvents,catalysts,oxidants were investigated.And controlled reaction under nitrogen atmosphere illustrated that C-S bond was formed via the oxidization by oxygen.Based on the results,water as the medium can promote KIO₃-catalyzed cross-dehydrogenative coupling reactions.