Electronic control of the reglochemistry in palladium - Phosphine catalyzed intermolecular heck reactions
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 0002-7863Full text not available from this repository.
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|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||JOURNAL OF THE AMERICAN CHEMICAL SOCIETY|
|Publisher:||AMER CHEMICAL SOC|
|Date:||9 June 2004|
|Number of Pages:||8|
|Page Range:||pp. 7144-7151|
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