Acetoxylation of arenes

Nuclear597 or side-chain588,598 acetoxylation of arenes can be performed with good yields by persulfate and copper(II) salts in acetic acid (equations 268 and 269). As previously shown for cyclohexene (equation 263), persulfate oxidizes the aromatic ring to a radical cation which loses a proton to give a carbon radical, which is further oxidized by copper(II) acetate to the final acetoxylated product. 

Eberson and co-workers590-594 have made detailed studies of the Pd(II)-catalyzed nuclear acetoxylation of arenes. The conditions for optimum yields of nuclear acetate were established using p-xylene as a model compound. It was... 

Bis-(2,2-dipyridyl)-silver(II) peroxydisulfate, Ag(dipy)2S2 0g. Mol. wt. 684.44. The reagent is prepared in the same way as the corresponding pyridine complex. Oxidative acetoxylation of arenes. This Ag(II) salt oxidizes arenes in acetic acid containing sodium acetate to acetoxyarenes usually in high yield. The... 

Acetoxylation of arenes. Arenes are acetoxylated by acetic acid (sodium acetate can be added) with potassium persulfate as oxidant and palladium(II) acetate as catalyst. The reaction is unusual in that wie/a-acetoxylation predominates this selectivity can be enhanced by addition of a complexing amine such as 2,2 -bipyridine. Side-chain acetoxylation can be effected with some arenes. Thus mesitylene and durene arc acetoxylated mainly in the a-position of the substituents. ... 

There is support for the occurrence of Pd(IV) species in the acetoxylation of arenes,t with the most recent proposal shown in Scheme 17, consistent with demonstrated palladation of benzene, for example, by Pd(02CMe)2/SEt2 to form... 

Table 1 Nuclear HOAc/0.5 M KOAc acetoxylation of arenes using Ag (bipy)2S20s in ...

The or//io-palladation of 3,4-dioxygenated benzylic tertiary amines by lithium tetrachloropalladate can be directed exclusively to either C-2 or C-6. Substitution at C-6 prevails when AcO, methylenedioxy, PhCH20, methoxymethyl ether, or HO substituents are attached to C-3, whereas palladation occurs exclusively at C-2 when C-3 bears methylthiomethyl ether or phenylthiomethyl ether substituents. The resulting organopalladium compounds are crystalline solids, stable to air and moisture, and can readily be carbonylated, alkylated, arylated, Kinetic studies of the acetoxylation of arenes by potassium peroxydisulphate and acetic acid in the presence of (2,2 -bipyridyl)palladium(ii) acetate catalyst have led to a revision of the mechanism. The reaction is now thought to proceed via... 

The acetoxylation of arenes tethered to 3,4-dihydroisoquinoline has been achieved using phenyliodonium acetate and acetic anhydride with a palladium acetate catalyst. 

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