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Electronic control of the reglochemistry in palladium - Phosphine catalyzed intermolecular heck reactions
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UNSPECIFIED (2004) Electronic control of the reglochemistry in palladium - Phosphine catalyzed intermolecular heck reactions. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 126 (22). pp. 7144-7151. ISSN 0002-7863.
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Abstract
Density functional theory calculations of the transition-state structures and reaction barriers for the C-C coupling between monosubstituted eta(2)-olefins and eta(1)-vinyl for neutral [Pdl(PH3)(vinyl)(RCHCH2)] and cationic [Pd (H2PCH2PH2)(vinyl)(RCHCH2)](+) (R = OMe, Me, and CN) depend mostly on the regiochemistry and not on the starting position of the olefin substituent. The regiochemistry is thus implicit in the electronic structure of the precursor complex. A selectivity index, Omega, based on electrostatic and frontier orbital interactions gives a good correlation with experiment for vinylations or arylations. The model correctly predicts that the regiochemistry for R = OMe, Me, and CN is the same for both neutral and cationic Pd complexes while for R = CH2OH the regiochemistry reverses. The latter is confirmed by explicit calculations of the transition-state energies. Selectivity indices are computed for 13 substituents: CO2Me, CN, CF3, Ph, H, Me, CH2OH, CH2NMe2, 2-pyrolidone, CH2SiMe3, OAc, OMe, and F. Cationic conditions systematically give larger Q values and thus tend to favor coupling at the a carbon on the olefin. The Omega values are approximately additive and can be used to predict the regiochemistry for disubstituted olefins.
Item Type: | Journal Article | ||||
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Subjects: | Q Science > QD Chemistry | ||||
Journal or Publication Title: | JOURNAL OF THE AMERICAN CHEMICAL SOCIETY | ||||
Publisher: | AMER CHEMICAL SOC | ||||
ISSN: | 0002-7863 | ||||
Official Date: | 9 June 2004 | ||||
Dates: |
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Volume: | 126 | ||||
Number: | 22 | ||||
Number of Pages: | 8 | ||||
Page Range: | pp. 7144-7151 | ||||
Publication Status: | Published |
Data sourced from Thomson Reuters' Web of Knowledge
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