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High-activity catalysts for Suzuki coupling and amination reactions with deactivated aryl chloride substrates: importance of the palladium source

High-activity catalysts for Suzuki coupling and amination reactions with deactivated aryl chloride substrates: importance of the palladium source
High-activity catalysts for Suzuki coupling and amination reactions with deactivated aryl chloride substrates: importance of the palladium source
A range of ortho-metalated catalysts with alkylphosphine ligands of the general formula [Pd(X)(kappa(2)N,C-C6H4CH2NMe2)(PR3)] have been synthesized, and the crystal structures of five examples (R = Cy, X = TFA, OTf, Cl, I; PR3 = PCy2(o-biphenyl), X = TFA) have been determined. The crystal structures of two dimeric precursor complexes, [{Pd(mu-TFA)(kappa(2)N,C-C6H4CH2NMe2)}(2)] and [{Pd(TFA)(kappa(2)N,C-C6H4CH=(NPr)-Pr-i)}(2)], have also been determined. The application of the phosphine adducts to both Suzuki coupling and Buchwald-Hartwig amination reactions with aryl chloride substrates was examined, and the performance of these catalysts versus conventional palladium sources was evaluated. In general the palladacyclic complexes show considerably enhanced activity. Typically, the best activity is seen with tricyclohexylphosphine adducts in Suzuki coupling and tri-tert-butylphosphine analogues in amination reactions. In nearly all the amination reactions performed, small amounts of a second product species were observed, namely 4,6-bis(aryl)-3,4-dihydro-2H[1,4]oxazines. The crystal structure of one example, 4,6-bis(4-methoxyphenyl)-3,4-dihydro-2H-[1,4]oxazine, was determined. Studies on the activation of palladacyclic precatalysts in the coupling of morpholine led to the isolation of a morpholine adduct, [Pd(TFA)(kappa(2)N,C-C6H5CH2NMe2){NH(CH2CH2)O}], which was structurally characterized by X-ray analysis.
room-temperature amination, arylboronic acids, bond formation, heck reaction, c-n, triarylphosphite complexes, cyclopalladated compounds, efficient catalysts, imine catalysts, palladacycles
0276-7333
987-999
Bedford, Robin B.
42532c45-cb80-48cd-9e93-8c2d5059eabe
Cazin, Catherine S.J.
5873f05c-dc1b-4af5-b6a2-70a619dcca0f
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Gelbrich, Thomas
42309d69-eaf1-4bb7-ba2e-db61f338e370
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Light, Mark E.
cf57314e-6856-491b-a8d2-2dffc452e161
Bedford, Robin B.
42532c45-cb80-48cd-9e93-8c2d5059eabe
Cazin, Catherine S.J.
5873f05c-dc1b-4af5-b6a2-70a619dcca0f
Coles, Simon J.
3116f58b-c30c-48cf-bdd5-397d1c1fecf8
Gelbrich, Thomas
42309d69-eaf1-4bb7-ba2e-db61f338e370
Horton, Peter N.
154c8930-bfc3-495b-ad4a-8a278d5da3a5
Hursthouse, Michael B.
57a2ddf9-b1b3-4f38-bfe9-ef2f526388da
Light, Mark E.
cf57314e-6856-491b-a8d2-2dffc452e161

Bedford, Robin B., Cazin, Catherine S.J., Coles, Simon J., Gelbrich, Thomas, Horton, Peter N., Hursthouse, Michael B. and Light, Mark E. (2003) High-activity catalysts for Suzuki coupling and amination reactions with deactivated aryl chloride substrates: importance of the palladium source. Organometallics, 22 (5), 987-999. (doi:10.1021/om020841+).

Record type: Article

Abstract

A range of ortho-metalated catalysts with alkylphosphine ligands of the general formula [Pd(X)(kappa(2)N,C-C6H4CH2NMe2)(PR3)] have been synthesized, and the crystal structures of five examples (R = Cy, X = TFA, OTf, Cl, I; PR3 = PCy2(o-biphenyl), X = TFA) have been determined. The crystal structures of two dimeric precursor complexes, [{Pd(mu-TFA)(kappa(2)N,C-C6H4CH2NMe2)}(2)] and [{Pd(TFA)(kappa(2)N,C-C6H4CH=(NPr)-Pr-i)}(2)], have also been determined. The application of the phosphine adducts to both Suzuki coupling and Buchwald-Hartwig amination reactions with aryl chloride substrates was examined, and the performance of these catalysts versus conventional palladium sources was evaluated. In general the palladacyclic complexes show considerably enhanced activity. Typically, the best activity is seen with tricyclohexylphosphine adducts in Suzuki coupling and tri-tert-butylphosphine analogues in amination reactions. In nearly all the amination reactions performed, small amounts of a second product species were observed, namely 4,6-bis(aryl)-3,4-dihydro-2H[1,4]oxazines. The crystal structure of one example, 4,6-bis(4-methoxyphenyl)-3,4-dihydro-2H-[1,4]oxazine, was determined. Studies on the activation of palladacyclic precatalysts in the coupling of morpholine led to the isolation of a morpholine adduct, [Pd(TFA)(kappa(2)N,C-C6H5CH2NMe2){NH(CH2CH2)O}], which was structurally characterized by X-ray analysis.

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Published date: 3 March 2003
Keywords: room-temperature amination, arylboronic acids, bond formation, heck reaction, c-n, triarylphosphite complexes, cyclopalladated compounds, efficient catalysts, imine catalysts, palladacycles

Identifiers

Local EPrints ID: 19903
URI: http://eprints.soton.ac.uk/id/eprint/19903
ISSN: 0276-7333
PURE UUID: b8d98858-22b6-441b-9a51-1aa7c54f497c
ORCID for Simon J. Coles: ORCID iD orcid.org/0000-0001-8414-9272
ORCID for Peter N. Horton: ORCID iD orcid.org/0000-0001-8886-2016
ORCID for Mark E. Light: ORCID iD orcid.org/0000-0002-0585-0843

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Date deposited: 23 Feb 2006
Last modified: 16 Mar 2024 03:12

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Contributors

Author: Robin B. Bedford
Author: Catherine S.J. Cazin
Author: Simon J. Coles ORCID iD
Author: Thomas Gelbrich
Author: Peter N. Horton ORCID iD
Author: Mark E. Light ORCID iD

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