Rhodium-catalyzed [4+2] Cycloaddition Reaction Employing N-sulfonyl-1,2,3-triazole As Aza-[4C] Synthon

N-sulfonyl-1,2,3-triazole could equilibrate with diazaimine through Dimroth rearrangement,and in the presence of transition metal,it is able to efficiently converted to?-imine metallocarbene.Because of the electrophilicity of the carbene carbon and the nucleophilicity of the imino nitrogen,the?-imine metallocarbene intermediate is becoming a very usefull synthon to participate in many organic reactions,such as:cyclopropanation,X-H bond insertion reactions?X=C,N,or O?,transannulations,ylide formations,as well as some rearrangement reactions.In these reactions,N-sulfonyl-1,2,3-triazole has been mostly employed as a[1C]synthon,[2C]synthon,[3C]or aza-[3C]synthon,rare study was reported utilizing it as a aza-[4C]synthon.Therefore,rhodium-catalyzed synthesis of heterocyclic compounds from N-sulfonyl-1,2,3-triazole as[4C]synthon with 2H azirine and 1,3-dimethylindole respectly was studied in this thesis.?1?Based on the migration of acetoxy of?-imino rhodium carbene,with azadiene as the key intermediate,one-port synthesis of cis fused pyrimidine was achieved by rhodium catalyzed[4+2]cyclization reaction of N-sulfonyl-1,2,3-triazole and 2H azirine with excellent chemoselectivity and stereoselectivity.Optimization of reaction conditions illustrated that under nitrogen atmosphere,with 2 mol%of Rh₂?OAc?₄ as catalyst,DCM?0.2 M?as reaction solvent,heating in sealing tube at100?9 h,substrates would be transferred to the desired fused pyrimidine product in moderate to good yields.Moreover,treatment of the fused pyrimidine product by BF₃·Et₂O produced the seven-membered 1-H-1,4-diazepine,indicating the potential of the protocol in synthesis of N-heterocycle of middle size.?2?A[4+2]cycloaddition of azadiene and 1,3-disubstituted indole was realized and indole-fused-pyridine derivatives were obtained with pretty good region-and chemoselectivity.The optimal reaction conditions were established as following:2:1mol ratio of triazole and indole,DCE?0.2 M?as reaction solvent,1 mol%of Rh₂?OAc?₄ as a catalyst,reacting 4 h under 60 ^oC.The desired products could be generated in moderate to good yields under such mild conditions with good compatibility of functional groups.This thesis achieved two cases employing N-sulfonyl-1,2,3-triazole as[4C]synthon in the synthesis of N-heterocycles.Benefiting from the priority of the formation of azadiene in the reaction,this strategy was very chemoselective,and provided another effective tool for synthese of some other nitrogen-containing compounds.