Gold-Catalyzed Chemoselective Transformation Of Enyne-Lactone

Transition metal-catalyzed transformation of unsaturated bonds is an important research area in organic chemistry.Among the various transformations,gold-catalyzed cascade reaction of unsaturated eneyne is a hot reaction in the frontier research fields.Alkyne esters are very important substrates in materials chemistry,pharmaceutical chemistry and organic synthetic chemistry,which can undergo gold-catalyzed tandem reaction and then be rapidly converted into aromatic compounds,heterocyclic compounds and other important cyclic compounds.In this paper,we mainly focused on the gold-catalyzed chemoselective transformation of enyne-lactone and realized the selective syntheses of a series of aromatic compounds.We hope this paper will provide some references to reaction designing,catalyst choosing and condition screening in organic synthesis methodology.This thesis is mainly divided into the following two parts:1):Ph3PAuCl/AgSbF6-catalyzed selective construction of methyl naphthalates from enyne-lactoneIn this chapter,we first summarized the research progress on the acyloxycarbocation intermediate,and then introduced our study on the reaction of enyne-lactone in detail.The reaction was initiated with a 6-endo-dig cyclization of the enyne-lactone substrate under the catalysis of gold catalyst,followed by ring fragmentation to form the nine-membered ring 2-oxo-oxoninium intermediate.Subsequently,a 6?electrocyclization and aromatization process occurred to produce the final naphthalene derivatives.A tandem 5-exo-dig cyclization/intramolecular Friedel–Crafts reaction was also possible,which led to polycyclic compounds.By screening the reaction conditions,we found that naphthalene derivatives could be selectively synthesized in the Ph₃PAuCl/AgSbF₆ catalytic system.In addition,a series of subsequent derivatization reactions of the products were also carried out.2):SIPrAuCl/AgBF4-catalyzed selective construction of polycyclic compounds from enyne-lactoneIn this chapter,we first briefly summarized some research progress on polycyclic compounds.Next,we further introduced our research on the synthesis of polycyclic compounds,which was obtained as a byproduct in the Ph₃PAuCl/AgSbF₆ catalytic system.Through a broad conditional screening,we found that polycyclic compounds could be selectively synthesized in the SIPrAuCl/AgBF₄ catalytic system.Some simple derivatization reactions of the polycyclic compounds were also carried out.At last,a tentative reaction mechanism was proposed,and an explanation of the chemoselectivity in these two different catalytic systems was given from a qualitative angle by combining the experimental results with possible mechanism.