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DOI: 10.1055/s-2006-941594
trans-Dichloro-bis(benzonitrile)palladium(II): A Versatile Reagent in Organic Synthesis
Publication History
Publication Date:
22 May 2006 (online)
Biographical Sketches
Introduction
The use of Pd(II) complexes as catalysts in organic reactions has been well-established since the beginnings of organic synthesis. Due to its versatility, trans-dichloro-bis(benzonitrile)palladium(II) receives special attention as activating agent and also as stabilizing agent. Recently, Khinast and his coworkers reacted ligands like (N-[3-(trimethoxysilyl)propyl]ethylenediamine, 2-(2¢-pyridyl)ethyltrimethoxysilane, etc. with Pd(PhCN)2Cl2 to prepare immobilized catalysts with improved activity in Suzuki coupling reactions. [1] The presence of polar groups in the ligand can increase the interaction of the metal complexes with a substrate which is able to improve enantioselectivity in asymmetric catalysis. [2] With this aim Condom et al. used Pd(PhCN)2Cl2 for the synthesis of the new asymmetric, water-soluble phosphine (S)-(-)-(3-diphenylphosphino-2-hydroxy-propyl)trimethylammonium chloride from the accessible (S)-(-)-(3-chloro-2-hydroxypropyl)trimethylammonium chloride. [3]
Various fluorinated arene ligands based on diimine and diacetylpyridine backbones, synthesized using Pd(PhCN)2Cl2, serve as precursor compounds for the investigations of π -stacking interaction. Pd(PhCN)2Cl2 is suitable for single-crystal X-ray diffraction studies, obtained by the growth from solution in benzonitrile, as it readily loses benzonitrile to form the cubic cluster Pd6Cl12, which co-crystallizes with a variety of planar aromatic hydrocarbons. [4]
Pd(PhCN)2Cl2 appears to be a versatile activating agent for the alcoholic and epoxide functionality under unusually mild conditions. [5] Another important aspect of this reagent is that it can be used as stabilizing agent for unstable azirine compounds via formation of 1:2 and 1:1 complexes. [6]
This reagent is generally prepared by condensation of PdCl2 in benzonitrile and it is also commercially available.
Abstracts
(A) Pd(PhCN)2Cl2 in combination with P(t-Bu)3, indeed a highly active catalyst for Sonogashira couplings, provides a mild, efficient and general method for the reaction of aryl bromides at room temperature. [7] Pd(PhCN)2Cl2/P(t-Bu)3 can even effect Sonogashira coupling of hindered aryl bromides. |
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(B) Reaction of Pd(PhCN)2Cl2 with the ligand LL [3-C6H4(CONMe-4-C5H4N)2] gave the neutral dipalladium(II) macrocycle trans,trans-[Pd2Cl4(µ-LL)2], with a short separation between the palladium atoms of the lantern complex [Pd2(µ-LL)4]4+, which acts as a host for chloride ions and forms the complex [Pd2(µ-Cl)(µ-LL)4]3+, in which the distance between the palladium atoms is significantly larger [Pd-Pd = 6.56 Å]. [8] |
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(C) Miura’s group reacted various aroyl chlorides (1) with styrene (2a) in the presence of the catalyst system Pd(PhCN)2Cl2/(PhCH2)Bu3NCl to give the corresponding stilbene derivatives 3a in satisfactory yields. The aroyl chlorides 1 also reacted with butyl acrylate (2b) to afford butyl (E)-cinnamate and its derivatives (3b) in 79-95% yields. [9] |
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(D) Pd(PhCN)2Cl2 in the presence of polyvinylpyrrolidone (PVP) as a polymer support is an efficient catalyst for the direct synthesis of diphenyl carbonate (DPC) via oxidative carbonylation of phenol using carbon monoxide and air. This is the first example of the successful usage of polymer support in the oxidative carbonylation yielding DPC. [10] |
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(E) Recently Ray et al. used Pd(PhCN)2Cl2 to stabilize azirines containing an aldehyde functionality via the formation of 2:1 and 1:1 complexes. [11] |
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(G) The group of McNulty and Capretta described the synthesis of a small library of phosphorinanes and demonstrated their utility in cross-coupling chemistry using Pd(PhCN)2Cl2. The phosphorinanes allowed for modification of one of the alkyl moieties permitting steric and electronic fine-tuning of the ligands. In addition, optimization revealed that Pd(PhCN)2Cl2 was the best palladium source for these couplings. [12] |
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- 1
Vassylyev O.Chen J.Panarello AP.Khinast JG. Tetrahedron Lett. 2005, 46: 6865 - 2
Yamada I.Ohkouchi M.Yamaguchi M.Yamagishi T. J. Chem. Soc., Perkin Trans. 1 1997, 1869 - 3
Condom M.Suades J. Inorg. Chem. Commun. 2005, 8: 355 - 4
Olmstead MM.Wei P.-P.Ginwalla AS.Balch AL. Inorg. Chem. 2000, 39: 4555 - 5
Mincione E.Ortaggi G.Sirna A. J. Org. Chem. 1979, 44: 1569 - 6
Hassner A.Bunnell CA.Haltiwanger K. J. Org. Chem. 1978, 43: 57 - 7
Hundertmark T.Littke AF.Buchwald SL.Fu GC. Org. Lett. 2000, 2: 1729 - 8
Yue NLS.Eisler DJ.Jennings MC.Puddephatt RJ. Inorg. Chem. Commun. 2005, 8: 31 - 9
Sugihara T.Satoh T.Miura M. Tetrahedron Lett. 2005, 46: 8269 - 10
Ishii H.Ueda M.Takeuchi K.Asai M. Catal. Commun. 2001, 2: 17 - 11
Brahma S.Ray JK. Tetrahedron Lett. 2005, 46: 6575 - 12
Brenstrum T.Clattenburg J.Britten J.Zavorine S.Dyck J.Robertson AJ.McNulty J.Capretta A. Org. Lett. 2006, 8: 103
References
- 1
Vassylyev O.Chen J.Panarello AP.Khinast JG. Tetrahedron Lett. 2005, 46: 6865 - 2
Yamada I.Ohkouchi M.Yamaguchi M.Yamagishi T. J. Chem. Soc., Perkin Trans. 1 1997, 1869 - 3
Condom M.Suades J. Inorg. Chem. Commun. 2005, 8: 355 - 4
Olmstead MM.Wei P.-P.Ginwalla AS.Balch AL. Inorg. Chem. 2000, 39: 4555 - 5
Mincione E.Ortaggi G.Sirna A. J. Org. Chem. 1979, 44: 1569 - 6
Hassner A.Bunnell CA.Haltiwanger K. J. Org. Chem. 1978, 43: 57 - 7
Hundertmark T.Littke AF.Buchwald SL.Fu GC. Org. Lett. 2000, 2: 1729 - 8
Yue NLS.Eisler DJ.Jennings MC.Puddephatt RJ. Inorg. Chem. Commun. 2005, 8: 31 - 9
Sugihara T.Satoh T.Miura M. Tetrahedron Lett. 2005, 46: 8269 - 10
Ishii H.Ueda M.Takeuchi K.Asai M. Catal. Commun. 2001, 2: 17 - 11
Brahma S.Ray JK. Tetrahedron Lett. 2005, 46: 6575 - 12
Brenstrum T.Clattenburg J.Britten J.Zavorine S.Dyck J.Robertson AJ.McNulty J.Capretta A. Org. Lett. 2006, 8: 103