Disodium Tetrachloropalladate(II)1

Na2PdCl4

[13820-53-6]  · Cl4Na2Pd  · Disodium Tetrachloropalladate(II)  · (MW 294.20)

(can cyclopalladate aromatic and heteroaromatic compounds;2 homogeneous catalyst for vinylation of imides and lactams;3 homogeneous catalyst for carbonylation of allyl chlorides;4 catalyst for oxidation of alkenes to ketones5)

Solubility: very sol H2O; slightly sol ethanol, acetone, acetic acid.

Form Supplied in: brown-red solid. Drying: at 100 °C/0.1 mmHg for 24 h.

Preparative Method: very often prepared in situ from 1 equiv of Palladium(II) Chloride and 2 equiv of Lithium Chloride in the appropriate solvent (MeOH, EtOH, MeCO2H).

Handling, Storage, and Precautions: is hygroscopic and should be stored in the absence of moisture. The trihydrate is formed in aqueous solution. Toxicity data are not available.

Organopalladium Reagents.

Various aromatic and heteroaromatic compounds containing nitrogen and sulfur atoms undergo cyclopalladation upon treatment with Na2PdCl4 to form dimeric complexes (eq 1).6 Similarly, oximes of a,a-dialkyl ketones react with Na2PdCl4 to give five-membered ring palladacycles.7 These complexes are readily oxidized to the b-acetoxy oximes (eq 2). Functionalized hexopyranosides can be prepared using this reaction.8

Alkenes react with Na2PdCl4 to give p-complexes,9 p-allyl complexes,10 or p-benzyl complexes,11 depending on nature of the compound. p-Allyl complexes are readily available by coupling of arylmercurials with alkenes.12 These complexes are electrophilic in character and react with a variety of nucleophiles.13

Vinylation and Carbonylation.

Imides and lactams are converted to N-vinyl derivatives when heated with Vinyl Acetate in the presence of Na2PdCl4 (eq 3).3 Allylic halides can be carbonylated at atmospheric pressure in the presence of Na2PdCl4 to form either b,g-unsaturated acids or esters (eq 4).4 Aromatic aldehydes can be carbonylated in the presence of amines to afford a-keto amides.14

Oxidations.

Oxidations are usually with either t-Butyl Hydroperoxide or Hydrogen Peroxide in conjunction with Na2PdCl4 as a catalyst. Simple alkenes give mixtures of products by this method.15 a,b-Unsaturated esters and ketones are oxidized to b-keto esters and b-diketones, respectively.5 a,b-Unsaturated phosphonates give b-ketophosphonates (eq 5).16


1. (a) Heck, R. F. Palladium Reagents in Organic Syntheses; Academic: London, 1985. (b) Maitlis, P. M. The Organic Chemistry of Palladium; Academic: New York, 1971. (c) Tsuji, J. Organic Synthesis with Palladium Compounds; Springer: Berlin, 1980. (d) Ryabov, A. D. S 1985, 233. (e) Gmelin Handbook of Inorganic Chemistry; Springer: Berlin, 1986; Pt Suppl. Vol. A1, pp 299-308. (f) Chemistry of the Platinum Group Metals; Hartley, F. R., Ed.; Elsevier: Amsterdam, 1991.
2. (a) Omae, I. CRV 1979, 79, 287. (b) Newkome, G. R.; Puckett, W. E.; Gupta, V. K.; Kiefer, G. E. CRV 1986, 86, 451. (c) Dunina, V. V.; Zalevskaya, O. A.; Potapov, V. M. RCR 1988, 57, 250. (d) Ryabov, A. D. CRV 1990, 90, 403.
3. Bayer, E.; Geckeler, K. AG(E) 1979, 18, 533.
4. (a) Okano, T.; Okabe, N.; Kiji, J. BCJ 1992, 65, 2589. (b) Kiji, J.; Okano, T.; Konishi, H.; Nishiumi, W. CL 1989, 1873.
5. Tsuji, J.; Nagashima, H.; Hori, K. CL 1980, 257.
6. (a) Tani, K.; Brown, L. D.; Ahmed, J.; Ibers, J. A.; Yokota, M.; Nakamura, A.; Otsuka, S. JACS 1977, 99, 7876. (b) Davis, R. C.; Grinter, T. J.; Leaver, D.; O'Neil, R. M.; Thomson, G. A. JCR(S) 1987, 280.
7. (a) Baldwin, J. E.; Jones, R. H.; Najera, C.; Yus, M. T 1985, 41, 699. (b) Baldwin, J. E.; Najera, C.; Yus, M. CC 1985, 126.
8. Rocherolle, V.; Lopez, J. C.; Olesker, A.; Lukacs, G. CC 1988, 513.
9. (a) Kauffmann, T.; Gaydoul, K. R. TL 1985, 26, 4071. (b) Wipke, W. T.; Goeke, G. L. JOC 1975, 40, 3242.
10. (a) Akermark, B.; Akermark, G.; Hegedus, L. S.; Zetterberg, K. JACS 1981, 103, 3037. (b) Söderberg, B. C.; Akermark, B.; Chen, Y. H.; Hall, S. S. JOC 1990, 55, 1344.
11. Rozenberg, V. I.; Nikanorov, V. A.; Gavrilova, G. V.; Gushchin, V. V.; Bakhmutov, V. I.; Reutov, O. A. IZV 1986, 2393.
12. Nizova, G. V.; Shul'pin, G. B. IZV 1987, 2070.
13. (a) Trost, B. M.; Weber, L.; Strege, P. E.; Fullerton, T. J.; Dietsche, T. J. JACS 1978, 100, 3416. (b) Trost, B. M.; Keinan, E. JOC 1979, 44, 3451.
14. Ozawa, F.; Yamagami, I.; Nakano, M.; Fujisawa, F.; Yamamoto, A. CL 1989, 125.
15. Antonsson, T.; Hansson, S.; Moberg, C. ACS 1985, B39, 593.
16. Poss, A. J.; Smyth, M. S. SC 1987, 17, 1735.

Valeri Martichonok

University of Toronto, Ontario, Canada



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