Copper-catalyzed stereoselective conjugate addition of alkylboranes to alkynoates

Abstract

SummaryA copper-catalyzed conjugate addition of alkylboron compounds (alkyl-9-BBN, prepared by hydroboration of alkenes with 9-BBN-H) to alkynoates to form β-disubstituted acrylates is reported. The addition occurred in a formal syn-hydroalkylation mode. The syn stereoselectivity was excellent regardless of the substrate structure. A variety of functional groups were compatible with the conjugate addition.

Copper-Catalyzed Semihydrogenation of Internal Alkynes with Molecular Hydrogen

“…Here, we disclose results of our independent work on the development of copper-catalyzed semihydrogenation of internal alkynes using molecular hydrogen . Use of a commercially available simple NHC ligand and the effectiveness of hydrogen gas at atmospheric pressure are practical merits of this protocol.…”

“…The nature of the base had a strong impact on the product yield (Table , entries 11–14) . The use of the sterically smaller base NaOMe instead of NaO t Bu decreased the product yield (entry 11).…”

Intermolecular Photocatalytic Chemo‐, Stereo‐ and Regioselective Thiol–Yne–Ene Coupling Reaction

“…Along with the generally accepted C−C cross‐coupling reactions involving unsaturated hydrocarbons with leaving groups (Sonogashira, Suzuki, Heck and other reactions), alternative methods of direct atom‐economical ene–ene, ene–yne and yne–yne couplings were developed [8–12] . These methods provide a great variety of possible products; however, at the same time, the control of chemo‐, regio‐ and stereoselectivity in these reactions becomes challenging, especially in the case of intermolecular processes [13–20] . In recent years, alkynes have also undergone a renaissance in the chemistry of radical photochemical processes involving metal complexes, since the triple bond is a convenient platform for selective bifunctionalization through C−C bond creation [21–24] …”

Intermolecular Photocatalytic Chemo‐, Stereo‐ and Regioselective Thiol–Yne–Ene Coupling Reaction

“…[8][9][10][11][12] These methods provide a great variety of possible products; however, at the same time, the control of chemo-, regio-and stereoselectivity in these reactions becomes challenging, especially in the case of intermolecular processes. [13][14][15][16][17][18][19][20] In recent years, alkynes have also undergone a renaissance in the chemistry of radical photochemical processes involving metal complexes, since the triple bond is a convenient platform for selective bifunctionalization through CÀ C bond creation. [21][22][23][24] The thiol-yne reaction is one of the most well-known processes in radical chemistry (Scheme 1A).…”

“…Along with the generally accepted C−C cross‐coupling reactions involving unsaturated hydrocarbons with leaving groups (Sonogashira, Suzuki, Heck and other reactions), alternative methods of direct atom‐economical ene–ene, ene–yne and yne–yne couplings were developed [8–12] . These methods provide a great variety of possible products; however, at the same time, the control of chemo‐, regio‐ and stereoselectivity in these reactions becomes challenging, especially in the case of intermolecular processes [13–20] . In recent years, alkynes have also undergone a renaissance in the chemistry of radical photochemical processes involving metal complexes, since the triple bond is a convenient platform for selective bifunctionalization through C−C bond creation [21–24] …”