Palladium-catalyzed C–H Bond Activation To Synthesize Dibenzothiophenes

C–H bond is the most common chemical bonds in organic compounds.It is an effective and clean method to construct C–C bonds and C–X bonds by directly using C–H bond acitivation and realize the reactions of various functional groups.In recent years,palladium catalyzed C–H activation has developed rapidly.Compared with the traditional palladium catalyzed coupling reaction,the C–H activation reaction has a unique reaction route,shorter,higher economic,less by-products,and friendly to the environment.Our group also studied the palladium catalyzed hydrocarbon bond reaction and synthesis of heterocyclic compounds in depth,and provided an effective method for the rapid and efficient synthesis of heterocyclic compounds.Base on these,my thesis focuses its attention on a novel palladium-catalyzed crossing reaction of halogenated benzene,explored the synthesis of dibenzothiophene via 2-iodinated diaryl thioether under mild reaction conditions and the contents are as follows:Firstly,ortho iodo diaryl thioethers were synthesized via Williamson reaction,nitro reduction reaction,diazo reaction and iodination reaction.Using ortho iodo diaryl thioether,we have established the optimized conditions is that Pd3(dba)2(0.2 equiv.)as the catalyst,anhydrous Cu(OAc)2(0.2 equiv.)as additive,1 equiv.sodium pivalate hydrate as base,DMF as solvent.At best conditions,we have obtained 9 different dibenzothiophenes which were confirmed by m.p.and NMR.Our method merits as such advantages,high yield,short reaction time,cost-effectiveness and versatility in substrates.