Geminal dimetalation of alkylidene-type carbenoids with silylboranes and diborons
摘要:
A novel and efficient method for gem-dimetalation of carbenoids has been demonstrated. Treatment of alkylidene-type lithium carbenoids with such an interelement compound as silylborane or diboron to generate the corresponding borate complex, followed by warming to room temperature, induced migration of the silyl or boryl group from a negatively charged boron atom to the carbenoid carbon to afford 1-boryl-1-silyl-1-alkenes or 1,1-diboryl-1-alkenes in good yields. Carbon-carbon bond forming transformations of the gem-dimetalated compounds mediated by boron or silicon is also described. (C) 2002 Elsevier Science Ltd. All rights reserved.
Enantioselective Conjunctive Cross-Coupling of Bis(alkenyl)borates: A General Synthesis of Chiral Allylboron Reagents
作者:Emma K. Edelstein、Sheila Namirembe、James P. Morken
DOI:10.1021/jacs.7b01774
日期:2017.4.12
conjunctive cross-coupling is used for the synthesis of enantioenriched allylboron reagents. This reaction employs nonsymmetric bis(alkenyl)borates as substrates and appears to occur by a mechanism that involves selective activation of the less substituted alkene followed by migration of the more substituted alkene during the course of a Pd-induced metalate rearrangement.
Reaction Pathways and Redox States in α‐Selective Cobalt‐Catalyzed Hydroborations of Alkynes
作者:Clemens K. Blasius、Vladislav Vasilenko、Regina Matveeva、Hubert Wadepohl、Lutz H. Gade
DOI:10.1002/anie.202009625
日期:2020.12.14
Cobalt(II) alkyl complexes supported by a monoanionic NNN pincer ligand are pre‐catalysts for the regioselective hydroboration of terminal alkynes, yielding the Markovnikov products with α:β‐(E) ratios of up to 97:3. A cobalt(II) hydride and a cobalt(II) vinyl complex appear to determine the main reaction pathway. In a background reaction the highly reactive hydrido species specifically converts to
Alkynedehydrogenativeborylation and hydroboration: A catalytic amount of a dicationic Zn2+ complex, [TPPh ⋅ Zn]2+, selectively catalyzed the dehydrogenativeborylation of terminalalkynes with HBPin at room temperature while lower [TPPh ⋅ Zn]2+ loading sborylation step.
important pillars in organic chemistry, and one of these privileged structural motifs are allylic alcohols. The method of choice to date for the synthesis of these is the Nozaki–Hiyama–Takai–Kishi reaction. We describe here a valuable alternative to the synthesis of allylic alcohols via 1,2-metallate rearrangement. In this work, various vinyl boronic esters with different functional groups have been applied