Copper-Catalyzed 1,1-Boroalkylation Of Terminal Alkynes

Alkenylboronates are synthetically useful reagents in organic synthesis,This compound is typically a metal-catalyzed cross-interlaced reaction and is widely used in a variety of carbon-carbon and carbon-impurity combinations.In the process of producing diene,it is especially important to develop effective and practical synthetic alternatives to diene.In the end,it has been very common to report obtaining alkenyl boronic acid esters.Traditional methods include transition metal catalyzed hydroboration of terminal alkynes and doped dehydroboration.Moreover,transition-metal-catalyzed three-component borofunctionalization of unsaturated C-C bonds with an ex-ternal electrophile represents a straightforward strategy for the rapidly assembling multi-substituted alkenylboronates in a concise manner.A copper-catalyzed three-component reaction of terminal alkynes,diazo compounds and B₂pin₂ to prepare tri-substituted alkenylboronates has been developed:（1）A diazo compound is used as a carbene precursor to synthesize a Z-configuration alkenyl borate under the action of a copper catalyst.The substrate expansion of different electrical aryl diazoniums,aryl-terminal alkynes,and alkyl-terminal alkynes were carried out,and the yield can reach 95%.All products have satisfactory Z-selectivity.（2）The hydrazone derived from the aldehyde is used as the carbene precursor copper catalyst to synthesize E-configuration alkenyl borate,and the reaction substrates have been expanded to a certain extent.All substrates can reach a medium yield and good E-selectivity.Copper-catalyzed cross-coupling of terminal alkynes and carbene precursors to produce allene is a key step of this scheme.