Exceedingly facile (23 °C) and chemoselective H-CF3 activation with [(dppp)Pd(Ph)(OH)] in the presence of a Lewis base promoter such as n-Bu3P leads to Pd-CF3 bond formation in nearly quantitative yield. A combined experimental and computational study points to a new mechanism that involves H-bonding Pd-O(H)···H-CF3 and nucleophilic attack of the promoter on the metal, followed by a push-pull-type collapse of the resultant five-coordinate Pd(II) intermediate via a polar transition state.
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http://dx.doi.org/10.1021/ja409533s | DOI Listing |
J Org Chem
September 2024
School of Chemistry, University of Glasgow, Joseph Black Building, University Avenue, Glasgow G12 8QQ, U.K.
Conjugate addition of unstabilized Wittig-type phosphonium ylides to 1,1-diacceptor- and 1-acceptor-substituted alkenes is investigated by density functional theory and high-level (DLPNO-CCSD(T)) calculations. The results indicate that the initial conjugate addition step should be facile with barriers predicted to be between 0 and 21 kcal mol. Potential intramolecular follow-up reactions include the formation of acceptor-substituted cyclopropanes as well as the formation of dihydrofuran derivatives via intramolecular S2-type transition state structures.
View Article and Find Full Text PDFJ Am Chem Soc
November 2013
Institute of Chemical Research of Catalonia (ICIQ), Tarragona 43007, Spain.
Exceedingly facile (23 °C) and chemoselective H-CF3 activation with [(dppp)Pd(Ph)(OH)] in the presence of a Lewis base promoter such as n-Bu3P leads to Pd-CF3 bond formation in nearly quantitative yield. A combined experimental and computational study points to a new mechanism that involves H-bonding Pd-O(H)···H-CF3 and nucleophilic attack of the promoter on the metal, followed by a push-pull-type collapse of the resultant five-coordinate Pd(II) intermediate via a polar transition state.
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