Synthesis Of 5-Iodo-1,2,3,4-tetrahydropyridine Derivatives Via Rhodium-Catalyzed Transannulation Of 1-sulfonyl-1,2,3-triazoles

Metal carbene species is an important class of intermediate in organic synthesis.Recent years,?-imino metal carbene derived from 1-sulfonyl-1,2,3-triazoles has gained much attention.1-sulfonyl-1,2,3-triazoles can be easily obtained by Copper(I)catalyzed azide-alkyne cycloaddition,and converts into ?-imino diazo compound by Dimroth equilibrium.In the presence of Rh(II)catalyst,?-imino Rh(II)carbene would be formed.The ?-imino Rhodium carbene could undergo many typical carbene reactions,such as cyclopropanation,C-H,N-H,O-H insertion,1,2-migration and many other types of carbene-induced reactions.Compared to traditional donor/acceptor carbenes,the increased nucleophilicity of the nitrogen atom offers even more synthetic flexibility,allowing transannulation with many other compounds,such as nitriles,alkynes,allenes,isocyanates,aldehydes,furans,indoles and so on,to produce various useful N-heterocycles.In this thesis,we mainly demonstrate the rhodium catalyzed tandem intermolecular nuclephilic attack and intramolecular SN2 reactions of 1-sulfonyl-1,2,3-triazole and idodide for the synthesis of 5-iodo-1,2,3,4-tetrahydropyridines.First,a series of triazoles was successfully synthesized by using many types 4-pentyn-1-ols.Under a N2 atmosphere,3 mol% Rh2(esp)2 as catalyst in choloform,1-sulfonyl-1,2,3-triazole were converted into 5-iodo-1,2,3,4-tetrahydropyridines with iodides as nucleophile in good to excellent yields,and the reaction own a good functional group tolerance as well.Besides,the mechanism of the reaction was investigated,and an intermolecular nuclephilic attack and intramolecular SN2 pathway was proposed as the most plausible mechanism.Thus,sodium iodides was used for the first time as a nuclephile to trap an ?-imino rhodium carbene,and the synthetic utility of the products was demonstrated in cross-coupling reactions and the construction of biorelated polycyclic compounds.