Abstract
This contribution describes the reactivity of a zero-valent palladium phosphine complex with substrates that contain both an aryl halide moiety and an unsaturated carbon-carbon bond. Although η2-coordination of the metal center to a C=C or C≡C unit is kinetically favored, aryl halide bond activation is favored thermodynamically. These quantitative transformations proceed under mild reaction conditions in solution or in the solid state. Kinetic measurements indicate that formation of η2-coordination complexes are not nonproductive side-equilibria, but observable (and in several cases even isolated) intermediates en route to aryl halide bond cleavage. At the same time, DFT calculations show that the reaction with palladium may proceed through a dissociation-oxidative addition mechanism rather than through a haptotropic intramolecular process (i.e., ring walking). Furthermore, the transition state involves coordination of a third phosphine to the palladium center, which is lost during the oxidative addition as the C-halide bond is being broken. Interestingly, selective activation of aryl halides has been demonstrated by adding reactive aryl halides to the η2-coordination complexes. The product distribution can be controlled by the concentration of the reactants and/or the presence of excess phosphine.
| Original language | English |
|---|---|
| Pages (from-to) | 16113-16125 |
| Number of pages | 13 |
| Journal | Chemistry - A European Journal |
| Volume | 21 |
| Issue number | 45 |
| DOIs | |
| Publication status | Published - Nov 1 2015 |
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Keywords
- aryl halide activation
- bond activation
- coordination
- palladium
- rearrangement
ASJC Scopus subject areas
- Chemistry(all)
Cite this
Mechanistic Aspects of Aryl-Halide Oxidative Addition, Coordination Chemistry, and Ring-Walking by Palladium. / Zenkina, Olena V.; Gidron, Ori; Shimon, Linda J W; Iron, Mark A.; van der Boom, Milko.
In: Chemistry - A European Journal, Vol. 21, No. 45, 01.11.2015, p. 16113-16125.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Mechanistic Aspects of Aryl-Halide Oxidative Addition, Coordination Chemistry, and Ring-Walking by Palladium
AU - Zenkina, Olena V.
AU - Gidron, Ori
AU - Shimon, Linda J W
AU - Iron, Mark A.
AU - van der Boom, Milko
PY - 2015/11/1
Y1 - 2015/11/1
N2 - This contribution describes the reactivity of a zero-valent palladium phosphine complex with substrates that contain both an aryl halide moiety and an unsaturated carbon-carbon bond. Although η2-coordination of the metal center to a C=C or C≡C unit is kinetically favored, aryl halide bond activation is favored thermodynamically. These quantitative transformations proceed under mild reaction conditions in solution or in the solid state. Kinetic measurements indicate that formation of η2-coordination complexes are not nonproductive side-equilibria, but observable (and in several cases even isolated) intermediates en route to aryl halide bond cleavage. At the same time, DFT calculations show that the reaction with palladium may proceed through a dissociation-oxidative addition mechanism rather than through a haptotropic intramolecular process (i.e., ring walking). Furthermore, the transition state involves coordination of a third phosphine to the palladium center, which is lost during the oxidative addition as the C-halide bond is being broken. Interestingly, selective activation of aryl halides has been demonstrated by adding reactive aryl halides to the η2-coordination complexes. The product distribution can be controlled by the concentration of the reactants and/or the presence of excess phosphine.
AB - This contribution describes the reactivity of a zero-valent palladium phosphine complex with substrates that contain both an aryl halide moiety and an unsaturated carbon-carbon bond. Although η2-coordination of the metal center to a C=C or C≡C unit is kinetically favored, aryl halide bond activation is favored thermodynamically. These quantitative transformations proceed under mild reaction conditions in solution or in the solid state. Kinetic measurements indicate that formation of η2-coordination complexes are not nonproductive side-equilibria, but observable (and in several cases even isolated) intermediates en route to aryl halide bond cleavage. At the same time, DFT calculations show that the reaction with palladium may proceed through a dissociation-oxidative addition mechanism rather than through a haptotropic intramolecular process (i.e., ring walking). Furthermore, the transition state involves coordination of a third phosphine to the palladium center, which is lost during the oxidative addition as the C-halide bond is being broken. Interestingly, selective activation of aryl halides has been demonstrated by adding reactive aryl halides to the η2-coordination complexes. The product distribution can be controlled by the concentration of the reactants and/or the presence of excess phosphine.
KW - aryl halide activation
KW - bond activation
KW - coordination
KW - palladium
KW - rearrangement
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U2 - 10.1002/chem.201501580
DO - 10.1002/chem.201501580
M3 - Article
VL - 21
SP - 16113
EP - 16125
JO - Chemistry - A European Journal
JF - Chemistry - A European Journal
SN - 0947-6539
IS - 45
ER -