[42196-31-6] · C4F6O4Pd · Palladium(II) Trifluoroacetate · (MW 332.46)
Physical Data: mp 210 °C (dec).
Solubility: sol diethyl ether, acetone; insol benzene, chloroform, trifluoroacetic acid.
Form Supplied in: brown powder; commercially available.
Analysis of Reagent Purity: IR: n 1690, 1435 cm-1.
Preparative Methods: by reaction of Palladium(II) Acetate with excess Trifluoroacetic Acid on a steam bath, to yield a brown powder after drying in vacuo.1 The reagent is also prepared in 89% yield by reaction of Palladium(II) Chloride with aqueous hydrochloric acid, then 15% sodium hydroxide solution at 85 °C, followed by excess trifluoroacetic acid at 80 °C.2
Handling, Storage, and Precautions: stable solid; irritant and hygroscopic.
Photolysis of oxygenated acetone solutions of allylsilanes with an arylsulfonyl group at the allylic position in the presence of the title reagent (1) affords a,b-enals and a,b-enones (eq 1).3 Palladium(II) trifluoroacetate also catalyzes the oxidation of styrene to acetophenone in the presence of an oxygen atom donor such as a molozonide (2) (eq 2).4
The terminal allylic methyl group of geranylacetone is selectively oxidized with a catalytic amount of (1), 1,4-Benzoquinone as oxidant, o-methoxyacetophenone as added ligand, and acetic acid as solvent (eq 3).5
The 4-alkynyl-4-hydroxycyclobutenone ring system rearranges with ring expansion to alkylidenecyclopentenediones in the presence of (1) (eq 4).6 A similar selective ring expansion has provided 2-alkylideneindene-1,3-dione monoacetals (eq 5).6 In both cases the nonvinylic C-C bond migrates more rapidly.
Cyclization of a tetraene employing a catalytic amount of (1) with Triphenylphosphine as an additive in THF afforded a 73% yield of the cyclized and intramolecularly trapped diene (eq 6).7
The dimethyl ester of N-(ethoxycarbonyl)kainic acid forms a p-allyl palladium complex upon treatment with (1) followed by conversion to the more stable chloride complex.2 This p-allyl complex reacts with the anion of t-butyl acetoacetate to afford the alkylated product (eq 7).8
Palladium(II) Acetate is similar to palladium(II) trifluoroacetate. Comparable results are obtained in most of the reactions, except acetate is a better nucleophile than trifluoroacetate.
Michael H. Chen
Parke-Davis Pharmaceutical Research, Ann Arbor, MI, USA