Effects of B2pin2 and PCy3 on Copper-catalyzed Trifluoromethylation of Substituted Alkenes and Alkynes with the Togni Reagent
(English)Manuscript (preprint) (Other academic)
The copper-catalyzed oxytrifluoromethylation of phenylacetylenes and C-H trifluoromethylation of quinones were studied. It was found that both reactions are accelerated by B2pin2 and PCy3 additives. The two reactions have different substituent effects. The oxytrifluoromethylation is faster in the presence of electron donating groups, while the C-H trifluoromethylation is faster with electron withdrawing substituents. The Hammett plot for oxytrifluoromethylation gave a r value of -0.76 indicating that a positive charge is building up in the process. However, according to the absolute value of r the reaction probably does not proceed through a carbocation intermediate. The kinetic isotope effect measurements indicate that in C-H trifluoromethylation of quinones the cleavage of the C-H bond is not rate determining.
copper, trifluoromethylation, alkynes, quinones, mechanistic study, NMR study, deuterium labeling, Hammett
Research subject Organic Chemistry
IdentifiersURN: urn:nbn:se:su:diva-103101OAI: oai:DiVA.org:su-103101DiVA: diva2:715464