Palladium(II) Chloride-Silver(I) Acetate


[7647-10-1]  · Cl2Pd  · Palladium(II) Chloride-Silver(I) Acetate  · (MW 177.32) (AgOAc)

[563-63-3]  · C2H3AgO2  · Palladium(II) Chloride-Silver(I) Acetate  · (MW 166.92)

(catalyst system used for the allylic oxidation of alkenes and for altering the regioselectivity of intermolecular Heck reactions of allylic alcohols)

Physical Data: see Palladium(II) Chloride and Silver(I) Acetate.

Allylic Oxidation.

Treatment of alkenes with palladium chloride (5 mol %), silver acetate (10 mol %), tellurium oxide (5 mol %), and t-Butyl Hydroperoxide (50 mol %) in acetic acid affords allylic oxidation products.1 This procedure is especially useful for cyclic alkenes which fail to react with the Selenium(IV) Oxide-t-Butyl Hydroperoxide system for allylic oxidations (eq 1).

Two mechanisms appear to be operative depending on substrate structure. The reaction may proceed via either p-allyl palladium complexes2,3 (best explains compound (1), eq 2) or via acetoxypalladation followed by dehydropalladation4 (best explains compound (2), eq 3). The extent of regiocontrol is highly substrate dependent (eqs 2 and 3).

Intermolecular Heck Reactions.

Closely related to the palladium chloride/silver acetate catalyst system is the use of Palladium(II) Acetate/silver acetate in Heck reactions of aryl and vinyl halides. Silver carbonate is usually equally effective in this process (eqs 4 and 5). The use of silver acetate completely reverses the regioselectivity of b-hydride elimination in Heck reactions of allyl alcohols (eq 4).5,6

The stereochemistry of chiral allylic alcohols is maintained in the silver acetate promoted process (eq 5), indicating that reversible b-hydride elimination to the enol does not occur.7

Related Reagents.

Palladium(II) Acetate; Silver(I) Carbonate; Silver(I) Phosphate.

1. Uemura, S.; Fukuzawa, S.; Toshimitsu, A.; Okano, M. TL 1982, 23, 87.
2. Backvall, J. E.; Nordberg, R. E.; Bjorkmann, E. E.; Moberg, C. CC 1980, 943.
3. Hosokawa, T.; Uno, T.; Inui, S.; Murahashi, S. I. JACS 1981, 103, 2318.
4. Wolfe, S.; Campbell, P. G. C. JACS 1971, 93, 1497.
5. Jeffery, T. CC 1991, 324.
6. Jeffery, T. TL 1991, 32, 2121.
7. Jeffery, T. TL 1993, 34, 1133.

John Montgomery

Wayne State University, Detroit, MI, USA

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