Study On The Synthesis Of Indole-containing Polycycles From N-sulfonyl-1,2,3-triazoles

Recently,the transformations of N-sulfonyl-1,2,3-triazoles as diazo precursor has developed exponentially.Via Dimroth-type rearrangement,N-sulfonyl-1,2,3-triazoles could generateα-imino diazo compound.Catalyzed by transition metal catalysts（Rh,Ni,Ag,etc.）or Lewis acid（BF₃·Et₂O）,even directly heated,nitrogen can be removed givingα-imino carbene.It can undergo a series of different types of reactions,such as cycloaddition with double or triple bonds,insertion reaction to X-H or C-X,migration rearrangement reaction,it can also be empolyed in total synthesis of natural products.Polycycles containing indole skeleton is widespread in natural products and drugs.Concise,efficient and selective synthesis of such polycycle is of important significancy.In this thesis,reactions of N-sulfonyl-1,2,3-triazole and functionalized indoles were investigated to achieve synthesis of two classes of polycycles containing indole skeleton through different reaction modes.（1）Synthesis of tetrahydrocarbazole via Diels-Alder reaction of 2-（acrylate）indole and azadiene generated from 1,2-acyloxy migration of N-sulfonyl-1,2,3-triazole.The optimized reactions were established as that with 2 mol%Rh₂（OAc）₄ as catalyst,1,2-dichloroethane as solvent,triazole and indole was heated at 80℃,producing target tetrahydrocarbazole in good to excellent yields.The reaction went under mild conditions,the materials were available easily,the procedure was concise and the product could be transformed.These merits qualified the protocol a new and effective strategy for the synthesis of polycyclic compounds containing indole backbones.（2）Thermally induced metal-free spirocyclization of N-sulfonyl-1,2,3-triazole with 3-（2-isocyanoethyl）indole to produce[6,5,5,6]tetracyclic spirocyclic indole product containingα-carbazoline.The optimized reactions were established as that with chloroform and tetrahydrofuran as mixed solvent,triazole and indole was heated at 80℃in a sealed tube,producing spirocyclic indole product containingα-carbazoline in moderate to excellent yields with only one diastereoisomer generated for almost all cases,and the products could undergo a variety of transformations,illustrating the significant potential of this method in the synthesis of spirocyclic indole compounds.