substrates represents a major challenge of the present cross‐coupling methodology. The nickel‐catalyzed Kumada cross‐ coupling of tertiary alkyl Grignard reagents with arylbromides allows this difficult reaction with numerous different substrates. Optimal results were obtained using sterically demanding, bifunctional N‐heterocyclic carbene ligands.
Polycyclic Aromatic Hydrocarbons via Iron(III)-Catalyzed Carbonyl–Olefin Metathesis
作者:Christopher C. McAtee、Paul S. Riehl、Corinna S. Schindler
DOI:10.1021/jacs.7b01114
日期:2017.3.1
Polycyclicaromatichydrocarbons are important structural motifs in organic chemistry, pharmaceutical chemistry, and materials science. The development of a new syntheticstrategytoward these compounds is described based on the design principle of iron(III)-catalyzed carbonyl-olefin metathesis reactions. This approach is characterized by its operational simplicity, high functional group compatibility
In this study, nickel-catalyzedcoupling reactions between arylhalides and tert-alkyl Grignardreagents were developed. Our original bicyclic NHC ligands reduced the formation of isomerized products, and we found that NMP as a co-solvent suppressed the reduction process. Under the optimal conditions we developed, the catalyst loading was lowered to 0.5 mol %, and catalyst loading using ortho-substituted
Arynes, generated in situ from ortho-silylaryl triflates, undergo ene reaction with alkynes possessing propargylic hydrogen in the presence of KF/18-crown-6 in THF at room temperature to give substituted phenylallenes. Various terminal and internal alkynes as well as different arynes can be used to give the corresponding phenylallenes in good to moderate yields. The reaction of alkyne without propargylic