The Study On Aryl Sp~2 C-H Functionalization Via α-oxo Gold Carbene Generated In Situ From Alkyne

Gold is a kind of soft Lewis acid,which is known as"πacid"due to its unique electronic effect.Its complexes can be applied to alkynes addition,isomerization and other reactions.Gold carbene has be formed by the gold catalyst andπsystem,which is similar to the diazo carbonyl compounds,can be competent for almost occurrence reactions by the diazo carbonyl,but there is no the diazo carbonyl compounds in the difficult to generate,explosive,virulent and astable.The alkyne is readily available safe,which can construct carbonyl compounds by oxidation.It is one of the important tasks for the chemists to construct the carbonyl skeleton safely and economically with simple and easy material under the mild reaction conditions.The study onα-diazo carbonyl compounds strategy was main previously,but its obvious defects limited the large-scale production application.Therefore,it is necessary to develop a safe and effective method to synthesize the carbonyl skeleton.For the past dozen years,the strategy formingα-oxo gold carbene/carbenoids via homogeneous gold catalyst has been developed,which has a great advantage in the synthesis of natural products or bioactive molecules.In this paper,we study the activation alkynes of homogeneous gold catalysts,the generation ofα-oxo gold carbene intermediates by intermolecular oxidation,and the highly active electrophilic intermediate intramolecular trapping which the aryl as nucleophilic reagent.We have developed an approach to synthesize carbonyl compounds efficiently.The following is a brief summary of our research findings:1.In this paper,but-3-yn-1-ylbenzene was designed as a substrate,a new gold catalysis method for the study on aryl sp~2 C-H via theα-oxo gold carbene intermediate generated in situ from alkyne by intramolecular oxidation was developed,and 11 kinds of 2-Tetralone substituted compounds were synthesized successfully.These tetralone compounds are important intermediates for many natural products or drug molecules.At the same time,we found and studied Anti-Markovnikov addition which is the side reaction.2.We have further successfully synthesized 8 kinds of substituted phenanthren-9-ol compounds using this catalytic system.These substituted phenanthren-9-ol compounds have themselves certain biological activity,and also can be synthesized new drug molecules by convenient steps.Finally,we designed and explored the internal alkyne substrate.This synthesis method developed in this paper has the following advantages:It is necessary to overcome the difficulty for more flexible and weaker necleophile of alkyne substrates in the previous work,with bulky Ligand gold complex and synthesize substituted2-Tetralone and Phenanthren-9-ol,no extra acid addition,with high yield,safe operation,mild reaction condition,simple treatment,and the high atom economy.The possible reaction mechanism includes the formation ofα-oxo gold carbene via gold-catalyzed intermolecular alkynyl oxidation and intramolecular gold carbene trapping process.