Iron-Catalyzed Methylalumination Of Terminal Alkynes

Methyl-branched trisubstituted alkene moiety is a common chemical building block in biologically active natural products and drugs.Among various synthetic methods,carbometalation of alkynes is an efficient and convenient method to construct polysubstituted olefins.Among them,zirconium-catalyzed methylalumination of alkynes is an important method to synthesize trisubstituted olefins with methyl substituent,which has been widely used for the synthesis of natural products.With the development of late-transition metal catalytic reactions,finding a cheaper,easily available,and widely applicable catalyst is of great significance for the synthesis of trisubstituted olefins containing methyl substituent.In this dissertation,a highly stereoselective and regioselective methylalumination of terminal alkynes has been achieved under mild reaction conditions(50 ~oC),which using cheap and readily available anhydrous ferric chloride as catalyst,trimethylaluminium as methylation reagent,and 1,2-dichloroethane as solvent.By this method,a variety of trisubstituted olefins containing methyl substituent are synthesized.Verification experiment by stereoselectivity proved that the reaction has specific regioselectivity and high stereoselectivity.This method expands the type of catalysts for methylalumination of alkynes and provides a new method for the synthesis of methyl-branched trisubstituted olefins.