Nickel-Catalyzed <i>trans</i>-Alkynylboration of Alkynes via Activation of a Boron−Chlorine Bond
作者:Akihiko Yamamoto、Michinori Suginome
DOI:10.1021/ja055396z
日期:2005.11.1
Reaction of (diisopropylamino)chloroboryl ethers of alkynols with alkynylstannanes in the presence of nickel catalysts afforded formal trans-alkynylboration products in good yields. The products were isolated as pinacol boronates after treatment of the crude reaction mixture with acetic anhydride and pinacol in the presence of a base. The trans-alkynylboration products underwent Suzuki-Miyaura coupling reaction with organic halides. A 2-borylalkenylnickel(II) complex, in which the boryl and nickel groups are located in a trans fashion, was isolated in a reaction of the chloroboryl ether with a single equivalent of a nickel(0)-phosphine complex.
Palladium-Catalyzed <i>trans</i>- and <i>cis</i>-Carboboration of Alkynes Tethered to Chloroborane with Organozirconium Reagents: Ligand-Dependent Complementary Stereoselectivity
Cyclizative carboboration of carbon-carbon triple bonds has been achieved with a wide range of organozirconium reagents, including alkenyl, aryl, and alkylzirconium, with chloroboranes tethered to alkynes in the presence of palladium catalysts. The carboboration takes two distinctive stereochemical courses depending upon the phosphine ligands used: PMe3 induces highly selective cis-carboboration, while bulkier phosphines such as PtBu3, PCy3, and PAr3 induce trans-carboboration selectively.