Copper-Mediated Functionalization Of Unsaturated Carbon-Carbon Bonds

The addition reactions involving carbon-carbon unsaturated bonds are widely used to construct complex functional molecules and structural fragments in organic chemistry.Not only simple chain molecules,but also different cyclic molecules can be formed in this kind of reaction.The addition reaction of unsaturated bonds can form new carbon-carbon bonds and carbon-heteroatom bonds efficiently,such as carbon-silicon bond and carbon-boron bond.Silicon-and boron-containing molecules are easily converted into other useful compounds.The following three directions will be discussed for the study of copper-mediated/catalyzed synthesis of dihydropyrroles and organoboronates/organosilanes.We have developed an efficient protocol for the synthesis of various highly functionalized dihydropyrroles by copper.The method is a novel path for the preparation of dihydropyrrole derivatives and a successful application of generally disfavored 5-endo-trig radical cyclization.We chose N-allyl-N-vinyl acetamides and electron-deficient alkyl bromides as the substrates in the intermolecular reaction.The reaction could process smoothly with different substituted acetamides and electron-deficient alkyl bromides.It was promoted by copper instead of organotin.48%-90%target products could be obtained in our reaction.An efficient copper-catalyzed asymmetric synthesis of spiro compounds from 1,6-diynes is reported.This reaction processed cascade proto-silylation and cyclization.This kind of spiro compound bears two external olefins and one of the double bonds is connecting a silyl group.The optically active spiro compounds were formed by selectively reacting with one of the triple bonds first and cyclization and protonation process under chiral conditions.Besides,the vinylsilyl in the products have Z-configuration exclusively.In addition,1,3-diene products can be used to synthesize polycyclic compounds by reacting with varieties of dienophiles.Finally,we chose allenes as the substrates to realize the regioselective addition reaction by using copper as catalyst.We chose gem-difluoroallenes as substrates and the selective addition to the double bond farther away from fluorine atom is due to the LUMO of the gem-difluoroallene is on the remote double bond of fluorine atom.It is different from non-fluorine allenes that nucleophiles are added to y-position of gem-difluoroallenes to afford ?,?-addition products.The reaction has high substrates tolerance and regioselectivity.Not only monosubstituted gem-difluoroallenes but also disubstituted gem-difluoroallenes could react well with PhMe2Si-Bpin and bis(pinacolato)diboron(B2pin2).The protocol is simple and efficient to construct compounds that contain tertiary/secondary gem-difluoroallylboronates and gem-difluoroallylsilanes.Further,diverse organofluorine compounds can be converted from these organoboronates and silanes.