Rhodium And Gold Tandem Catalyzed Synthesis Of 2,5-Dihydropyrroles And 3-Aminofurans Heterocyclic

The nitrogen-containing and oxygen-containing heterocyclic compounds are a very important class of small organic molecules that are widely in nature, many of them have the biological activity and become core skeleton of pharmaceuticals, pesticides and functional materials. Therefore, to use Simple and easy access small molecular compounds as raw materials, development of simple, efficient, environmentally benign methods for synthesis of heterocyclic compounds has been received considerable attention in synthetic catalytic community. Because of the high efficiency, atom economy, tandem reaction has been considered as expeditious approach to construct complex molecules from simple feedstocks.In this thesis, a strategy on relayed rhodium and gold transition-metal catalyzed 2,5-dihydropyrroles and 3-aminofurans synthesis has been realized. This transformation involves a three-step-sequence to give the final heterocycles:(1) rhodium(?) catalyzed triazoles to generate aza-vinyl rhodium(?) carbine, (2) O-H bond insertion of propargyl alcohol to aza-vinyl rhodium(?) carbene intermediate, (3) thermal Claisen-type [3,3]-sigmatropic rearrangement, (4) gold(?)-catalyzed N- or O-cyclization of the in situ generated ?-allenyl ?-amino ketone. When ?-substituted propargyl alcohol was employed, N-cyclization would take place, leading to 2,5-dihydropyrrole selectively. In contrast, when propargyl alcohol bearing on substituents at propargyl position, O-cyclization would take place, thus leading to the formation of 3-aminofurans. Interestingly, according to mechanistic study, the reaction modes of N-cyclization or O-cyclization were not just simply controlled by the structure of the propargyl alcohols. More importantly, it was catalyst dependent, namely gold catalyst complex could alter the reaction pathway.In a word, a rapid approach to 2,5-dihydropyrroles and substituted 3-aminofurans derivatives via tandem reactions has been developed. This procedure features high efficiency, broad substrate scope and they was characterized by 1H NMR,13C NMR spectra, HRMS, FT-IR spectrometer, crystal structures?...