[72287-26-4]  · C34H28Cl2FeP2Pd  · Dichloro[1,1-bis(diphenylphosphino)ferrocene]palladium(II)  · (MW 731.72)

(catalyst for cross-coupling reactions)

Physical Data: mp 265-268 °C (dec).

Solubility: sol ether, THF, benzene.

Form Supplied in: reddish brown solid; commercially available.

Purification: recrystallization from CHCl3 under inert atmosphere.

Handling, Storage, and Precautions: the complex is an irritant; store under an inert atmosphere.

Cross Coupling.

Like other PdII and NiII phosphine complexes, PdCl2(dppf) is a very useful catalyst for the cross-coupling reactions of vinyl or aryl halides or triflates with Grignard reagents, leading to carbon-carbon bond formation.1 PdCl2(dppf)-catalyzed reaction of vinyl bromide with s-BuMgCl gives exclusively the desired coupling product (eq 1), while other Pd catalysts also yield isomerized and reduced by-products.1a (E)-1-Bromo-1-alkenes are more reactive than the (Z)-isomers.1c Selective monoalkylation of dichlorobenzene under refluxing conditions using PdCl2(dppf) catalyst has been recorded.2 Whereas palladium catalysts are usually unreactive in cross couplings of organosulfur compounds,3 reactions of 2-methylthio-4,4-dimethyl-2-oxazoline with aryl Grignard reagents are catalyzed efficiently by PdCl2(dppf) (eq 2).4 Phototoxic terthiophenes have been prepared and the SMe group remains intact under the reaction conditions (eq 3).5 Organozinc reagents behave similarly in these cross coupling reactions.6 PdCl2(dppf) has been found to catalyze iodine-zinc exchange reactions which lead to an interesting Pd-catalyzed intramolecular carbozincation of alkenes (eq 4).7 It is noteworthy that various functional groups remain intact under these conditions.

Aliphatic iodides are reduced upon treatment with alkyl Grignard reagents in the presence of PdCl2(dppf) catalyst.8 Aryl triflates are efficiently reduced by Sodium Borohydride or Ammonium Formate in the presence of PdCl2(dppf).9

PdCl2(dppf) also promotes the Stille reaction10,11 as well as the Suzuki reaction.12 Selective alkyl transfer in the Stille coupling reaction is effectively catalyzed by PdCl2(dppf) (eq 5).10a Distannanes have been found to promote the PdCl2(dppf) catalyzed allylation of aryl halides with allyl acetate.10b Intramolecular cyclization and cross coupling of alkynic aryl triflates with organotin reagents is promoted by PdCl2(dppf) (eq 6).10c The PdCl2(dppf)-catalyzed inter- and intramolecular coupling reactions of vinyl or aryl triflates with organostannanes in the presence of carbon monoxide and Lithium Chloride takes place under mild conditions to give good yields of vinyl or aryl ketones (eq 7).11 Similar reactions have been performed with aryl triflates (eq 8).13

The title reagent has also been used to hydroesterify trimethylsilylalkynes, affording conjugated vinylsilanes in good yield (eq 9).14

1. (a) Hayashi, T.; Konishi, M.; Kumada, M. TL 1979, 1871. (b) Hayashi, T.; Konishi, M.; Yokota, K-I.; Kumada, M. CL 1980, 767. (c) Rossi, R.; Carpita, A. TL 1986, 27, 2529. (d) Tamao, K.; Iwahara, T.; Kanatani, R.; Kumada, M. TL 1984, 25, 1909. (d) Hayashi, T.; Konishi, M.; Kobori, Y.; Kumada, M.; Higuchi, T.; Hirotsu, K. JACS 1984, 106, 158. (f) Hayashi, T.; Yamamoto, A.; Hagihara, T. JOC 1986, 51, 723.
2. Katayama, T.; Umeno, M. CL 1991, 2073.
3. Okamura, H.; Miura, M.; Takei, H. TL 1979, 43.
4. Pridgen, L. N.; Killmer, L. B. JOC 1981, 46, 5402.
5. (a) Rossi, R.; Carpita, A.; Ciofalo, M.; Lippolis, V. T 1991, 47, 8443. (b) Carpita, A.; Rossi, R.; Veracini, C. A. T 1985, 41, 1919.
6. (a) Asao, K.; Iio, H.; Tokoroyama, T. TL 1989, 30, 6401. (b) Campbell, J. B., Jr.; Firor, J. W.; Davenport, T. W. SC 1989, 19, 2265.
7. Stadtmüller, H.; Lentz, R.; Tucker, C. E.; Stüdemann, T.; Dörner, W.; Knochel, P. JACS 1993, 115, 7027.
8. (a) Yuan, K.; Scott, W. J. TL 1989, 30, 4779. (b) Yuan, K.; Scott, W. J. JOC 1990, 55, 6188.
9. Peterson, G. A.; Kunng, F.-A.; McCallum, J. S.; Wulff, W. D. TL 1987, 28, 1381.
10. (a) Vedejs, E.; Haight, A. R.; Moss, W. O. JACS 1992, 114, 6556. (b) Yokoyama, Y.; Ito, S.; Takahashi, Y.; Murakami, Y. TL 1985, 26, 6457. (c) Luo, F.-T.; Wang, R.-T. TL 1991, 32, 7703.
11. (a) Echavarren, A. M.; Stille, J. K. JACS 1988, 110, 1557. (b) Stille, J. K.; Su, H.; Hill, D. H.; Schneider, P.; Tanaka, M.; Morrison, D. L.; Hegedus, L. S. OM 1991, 10, 1993. (c) Torii, S.; Xu, L. H.; Okumoto, H. SL 1991, 695.
12. Miyaura, N.; Ishiyama, T.; Ishikawa, M.; Suzuki, A. TL 1986, 27, 6369. Miyaura, N.; Ishiyama, T.; Sasaki, H.; Ishikawa, M.; Satoh, M.; Suzuki, A. JACS 1989, 111, 314. Ishiyama, T.; Miyaura, N.; Suzuki, A. SL 1991, 687.
13. Echavarren, A. M.; Stille, J. K. JACS 1988, 110, 1557.
14. Takeuchi, R.; Sugiura, M.; Ishii, N.; Sato, N. CC 1992, 1358.

Tien-Yau Luh, Lung-Lin Shiu & Sue-Min Yeh

National Taiwan University, Taipei, Taiwan

Timothy T. Wenzel

Union Carbide Corporation, South Charleston, WV, USA

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