ZnI2/NaCNBH3 as an Efficient Reagent for Regioselective Ring Opening of the Benzylic Epoxide Moiety
In the presence of zinc iodide, sodium cyanoborohydride was found to produce regioselective ring opening of benzylic epoxides in mild reaction conditions.
Aromatic β-silylethenylation reactions via organogallium compounds
In the presence of GaCl3, silylethyne reacted electrophilically with aromatic hydrocarbons to give β-silylethenylated arenes. The reaction proceeded via cationic species generated by the interaction of GaCl3 and silylethyne. High reactivity of the intermediate was demonstrated by the rapid reaction rate at -78 °C using close to the equimolar amount of the substrates. ipso-Substitution reaction took place with 1,2,3- trimethoxybenzene. Structures and properties of several organogallium compounds involved in the reactions are discussed.
The scope of catalytic asymmetric hydroboration/oxidation with rhodium complexes of 1,1'-(2-diarylphosphino-1-naphthyl)isoquinolines
Preformed cationic Rh complexes of the title ligands are effective for the asymmetric hydroboration/oxidation of vinylarenes at ambient temperature. These vinylarenes may carry E- or Z-β substituents but not a substituents. Enantiomer excesses of up to 97% can be obtained in the most favourable cases. The enantioselectivity is moderately sensitive to the structure of the ligand: the difurylphosphino ligand gave superior results for electron-poor styrenes and the diphenylphosphino ligand the best results for electron-rich reactants. Mechanistic aspects are discussed.
Doucet, Henri,Fernandez, Elena,Layzell, Timothy P.,Brown, John M.