Synthesis Of 3-methylidene-2,3-dihydropyrroles Via Formal 1,2-enamine Migration/cyclization Cascade Of Rhodium Carbenes

N-sulfoyl-1,2,3-triazoles are easily available and stable to some extent.It could equilibrate withα-imino diazo compounds through Dimroth rearrangement,which can be used as diazo precusor.Under the catalysis of transion metals such as Rh,Au,Cu,Pd and Fe,α-imino diazo could generateα-imino metal carbene.The electrophilicity of carbene carbene carbon and the nucleophilicity of imino nitrogen inα-imino metal carbene bring it various reactivities.It could participate in X-H（X=C,N,O）bond insertion reactions,ylide formation and transformation,cyclopropanation and so on.Pyrrole exists widely in natural products and drug molecules,and its derivatives have good biological activity,so it is one of the most popular heterocyclic rings,and plays an important role in many fields.In this thesis,synthesis of 3-methylidene-2,3-dihydropyrroles via formal 1,2-enamine migration/cyclization reaction of rhodium carbenes was achieved.The optimized reaction conditions were as follows:under nitrogen,Rh₂（piv）₄ as the catalyst,DCE as the solvent,heated at 120℃in a sealed tube for 5 min,triazole containing enamine could be converted to stable 3-methylene pyrrole.The reaction could provide moderate to good yields.The reaction rate is fast and the substrate has good functional group compatibility.Due to the uniqueness of the extra-ring double bond,it is possible to introduce other functional groups further,illustrating the potential applications of the protocol in organic synthesis.