Cobalt‐Catalyzed Regio‐ and Stereoselective Hydroboration of Allenes
作者:Can Li、Zheng Yang、Lei Wang、Yinlong Guo、Zheng Huang、Shengming Ma
DOI:10.1002/anie.201915716
日期:2020.4.6
pincer-ligand-based cobalt-complex-catalyzed allenehydroboration affording Z-allylic boronates is described. The reaction demonstrates an excellent regio- as well as Z-stereoselectivity and a wide substrate scope that tolerates many functional groups. Based on solvent-assisted electrospray ionization mass spectrometry (SAESI-MS) studies, a rationale for the cobalt-catalyzed hydroboration involving the highly selective
Lewis Acid-Catalyzed Hydrometalation and Carbometalation of Unactivated Alkynes
作者:Naoki Asao、Yoshinori Yamamoto
DOI:10.1246/bcsj.73.1071
日期:2000.5
carbostannation of unactivatedalkynes with organosilanes, or organostannanes proceed effectively in the presence of catalytic amounts of Lewis acids to produce the corresponding vinylsilyl or vinylstannyl compounds in a highly regio- and stereoselective way. Although it is well known that transition metal catalyzed hydrometalations and carbometalations, in general, proceed in a cis-manner, the Lewis acid-catalyzed
Intermolecular [2 + 2] cycloaddition reaction of an allenyl silyl ether with vinyl ethers was realized on the basis of electrophilic activation of the allene by the platinum–phosphine catalyst, affording the corresponding methylenecyclobutanes in good yield. The use of the bulky trialkynylphosphine as a ligand was indispensable to achieve highly selective [2 + 2] cycloaddition.
A Pt(II)-catalyzed [3 + 2] cycloaddition reaction of silyl propadienyl ethers and alkenyl ethers has been developed as the first example of the utilization of allenes as a three-carbon unit in a transition-metal-catalyzed intermolecularcycloaddition reaction. Pt(II)-containing 1,3-dipole equivalents generated by electrophilic activation of silyl propadienyl ethers using a Pt(II) catalyst reacted with
Copper-Catalyzed Regio- and Stereoselective Three-Component Coupling of Allenyl Ethers with <i>gem</i>-Dichlorocyclobutenones and B<sub>2</sub>pin<sub>2</sub>
and stereoselective difunctionalization of allenes with allenyl ethers, bis(pinacolato)diboron, and gem-dichlorocyclobutenones as electrophiles was reported, yielding a variety of highly functionalized cyclobutenone products tethering with an alkenylborate fragment. The polysubstituted cyclobutenone products also underwent diverse transformations.