Study Of Gold-Catalyzed Cascade Reactions With Acetylene As Carbene Precursors For The Constrction Of Polycyclic Indole Derivatives

Different from diazo compounds,alkynes have been widely used as the important metal carbene precursors in modern organic synthesis with their safety,low toxicity and diversity.Recently,more and more attention has been paid on gold-catalyzed alkyne formed gold carbene,which has become one of the main branches in the field of metal carbene research.Reaction types include insertion,rearrangement,addition reaction,ect.It has gradually become a kind of efficient synthesis methods for the construction of complex structural compounds.This paper mainly focuses on the gold-catalyzed synthesis of a-imino and a-carbonyl carbene intermediates from alkynes and construction of heterocyclic compounds with various structures by intramolecular insertion reaction and intermolecular multi-component reaction.Part Ⅰ:This part has disclosed an unprecedented gold-catalyzed bicyclization reaction of diaryl alkynes for the synthesis of indole derivatives in good to high yields under mild reaction conditions.Mechanistically,this alkyne bifunctionalization transformation was terminated by a formal X-H insertion reaction,followed by 1,3-H shift to furnish to the corresponding polycyclic N-heterocycles with structural diversity,and the key intermediate 3H-indole was isolated and characterized for the first time.Part Ⅱ:The gold-catalyzed oxidation of propargyl alcohol to form an intermediate of a-carbonyl carbene,followed by the addition of intramolecular hydroxyl groups to form oxytantalum yelide,and finally the intermolecular Aldol addition with isatin to form 3-hydroxy indoles were studied.Compared with the traditional catalytic oxidation of alkynes via the intermediate of a-carbonyl carbene,we reported the first example of gold-catalyzed Aldol interception of yelide intermediate with alkynes as precursors of carbene.