Study On The Novel Synthesis Of Several Functionalized Carbocyclic Compounds

As a significant class of organic compounds,carbocyclic compounds widely exist in natural products,pharmaceuticals and functional materials,which have high research significance and application values in the fields of biology,material and synthesis.As a result,the development of economic and efficient methods for the construction of carbocyclic scaffold is one of the important tasks in organic synthesis.Based on these backgrounds,this thesis aims to the development of novel methods for the synthesis of several functionalized carbocyclic compounds and their derivatives from readily available starting materials allenic ketones via its cascade reactions under mild conditions.It includes the following two chapters:In the first chapter,a novel and efficient method for the construction of functionalized six-membered carbocyclic compounds via the one-pot three-component cascade reactions of allenic ketones with premary amines and enones is described.Mechanistically,the formation of the title compounds is initated by a nucleophilic addition of premary amine onto allenic ketone to afford an enaminone intermediate.The in situ formed enaminone then undergoes a nucleophilic addition onto enone.The thus formed addition adduct undergoes an intramolecular condensation to generate sustituted cyclohexa-1,3-diene.In the presence of TEMPO,a dehydrogenative aromatization occurs with the in situ formed poly-substituted cyclohexa-1,3-diene to give functionalized(2-aminophenyl)(phenyl)methanone.It is noteworthy that this reaction requires no metal catalyst or basic promoter.In the second chapter,an efficient and convenient synthesis of functionalized cyclobutane-fused naphthalene derivatives via cascade reactions of aryl-linked allenynes with tert-butyl nitrite is reported.Mechanistically,the formation of the title compounds proceeds through an intramolecular [2+2] cycloaddition of allenyne to afford a cyclobutane intermediate,followed by radical addition-coupling/oxidation reactions with tert-butyl nitrite to generate functionalized cyclobutanol-fused 2-nitronaphthalen-1-ol.In the presence of TEMPO,the tert-butylperoxyl radical,in situ formed by tert-butyl nitrite,will be inhibited by TEMPO which undergoes a radical coupling reation onto the cyclobutane intermediate to give nitro cyclobutane-fused naphthalenedione.Notably,the above reaction requires no metal catalyst.In summary,some novel synthetic methods for the preparation of functionalized carbocyclic compounds have been developed in this thesis: the synthesis of six-membered carbocyclic compounds from allenic ketone/allenoate,amine and enone,and the synthesis of functionalized four-membered carbocyclic compounds and their derivatives from aryl-linked allenynes and tert-butyl nitrile.Compared with literature methods,these new protocols have advantages such as cheap available starting materials,no requisite of metal-or base-catalyst,broad substrate scope,mild reaction conditions and good chemoselectivity.