Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes

Gerber, Roman; Oberholzer, Miriam; Frech, Christian M.

doi:10.1002/chem.201102936

Publication type:	Article in scientific journal
Type of review:	Peer review (publication)
Title:	Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes
Authors:	Gerber, Roman Oberholzer, Miriam Frech, Christian M.
DOI:	10.1002/chem.201102936
Published in:	Chemistry - A European Journal
Volume(Issue):	18
Issue:	10
Page(s):	2978
Pages to:	2986
Issue Date:	2012
Publisher / Ed. Institution:	Wiley
ISSN:	0947-6539 1521-3765
Language:	English
Subjects:	Catalysis; Brominated hydrocarbons; Nitriles; Organometallic compounds; Palladium
Subject (DDC):	540: Chemistry
Abstract:	Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium [(P{(NC(5)H(10))(C(6)H(11))(2)})(2)PdCl(2)] (1) is a highly active and generally applicable C-C cross-coupling catalyst. Apart from its high catalytic activity in Suzuki, Heck, and Negishi reactions, compound 1 also efficiently converted various electronically activated, nonactivated, and deactivated aryl bromides, which may contain fluoride atoms, trifluoromethane groups, nitriles, acetals, ketones, aldehydes, ethers, esters, amides, as well as heterocyclic aryl bromides, such as pyridines and their derivatives, or thiophenes into their respective aromatic nitriles with K(4)[Fe(CN)(6)] as a cyanating agent within 24 h in NMP at 140°C in the presence of only 0.05 mol % catalyst. Catalyst-deactivation processes showed that excess cyanide efficiently affected the molecular mechanisms as well as inhibited the catalysis when nanoparticles were involved, owing to the formation of inactive cyanide complexes, such as [Pd(CN)(4)](2-), [(CN)(3)Pd(H)](2-), and [(CN)(3)Pd(Ar)](2-). Thus, the choice of cyanating agent is crucial for the success of the reaction because there is a sharp balance between the rate of cyanide production, efficient product formation, and catalyst poisoning. For example, whereas no product formation was obtained when cyanation reactions were examined with Zn(CN)(2) as the cyanating agent, aromatic nitriles were smoothly formed when hexacyanoferrate(II) was used instead. The reason for this striking difference in reactivity was due to the higher stability of hexacyanoferrate(II), which led to a lower rate of cyanide production, and hence, prevented catalyst-deactivation processes. This pathway was confirmed by the colorimetric detection of cyanides: whereas the conversion of β-solvato-α-cyanocobyrinic acid heptamethyl ester into dicyanocobyrinic acid heptamethyl ester indicated that the cyanide production of Zn(CN)(2) proceeded at 25°C in NMP, reaction temperatures of >100°C were required for cyanide production with K(4)[Fe(CN)(6)]. Mechanistic investigations demonstrate that palladium nanoparticles were the catalytically active form of compound 1.
URI:	https://digitalcollection.zhaw.ch/handle/11475/9727
Fulltext version:	Published version
License (according to publishing contract):	Licence according to publishing contract
Departement:	Life Sciences and Facility Management
Appears in collections:	Publikationen Life Sciences und Facility Management

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Gerber, R., Oberholzer, M., & Frech, C. M. (2012). Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes. Chemistry - A European Journal, 18(10), 2978–2986. https://doi.org/10.1002/chem.201102936

Gerber, R., Oberholzer, M. and Frech, C.M. (2012) ‘Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes’, Chemistry - A European Journal, 18(10), pp. 2978–2986. Available at: https://doi.org/10.1002/chem.201102936.

R. Gerber, M. Oberholzer, and C. M. Frech, “Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes,” Chemistry - A European Journal, vol. 18, no. 10, pp. 2978–2986, 2012, doi: 10.1002/chem.201102936.

GERBER, Roman, Miriam OBERHOLZER und Christian M. FRECH, 2012. Cyanation of aryl bromides with K4[Fe(CN)6] catalyzed by Dichloro[bis{1-(dicyclohexylphosphanyl)piperidine}]palladium, a molecular source of nanoparticles, and the reactions involved in the catalyst-deactivation processes. Chemistry - A European Journal. 2012. Bd. 18, Nr. 10, S. 2978–2986. DOI 10.1002/chem.201102936

Gerber, Roman, Miriam Oberholzer, and Christian M. Frech. 2012. “Cyanation of Aryl Bromides with K4[Fe(CN)6] Catalyzed by Dichloro[bis{1-(Dicyclohexylphosphanyl)piperidine}]Palladium, a Molecular Source of Nanoparticles, and the Reactions Involved in the Catalyst-Deactivation Processes.” Chemistry - A European Journal 18 (10): 2978–86. https://doi.org/10.1002/chem.201102936.

Gerber, Roman, et al. “Cyanation of Aryl Bromides with K4[Fe(CN)6] Catalyzed by Dichloro[bis{1-(Dicyclohexylphosphanyl)piperidine}]Palladium, a Molecular Source of Nanoparticles, and the Reactions Involved in the Catalyst-Deactivation Processes.” Chemistry - A European Journal, vol. 18, no. 10, 2012, pp. 2978–86, https://doi.org/10.1002/chem.201102936.