Palladium catalysis alkene acetalization

In contrast, the closely related palladium acetate-promoted intramolecular alkylation of alkenes by tri-methylsilyl enol ethers (Scheme 4)6,7 has been used to synthesize a large number of bridged carbocyclic systems (Table 1). In principle, this process should be capable of being made catalytic in palladium(II), since silyl enol ethers are stable to a range of oxidants used to carry the Pd° -> Pd11 redox chemistry required for catalysis. In practice, catalytically efficient conditions have not yet been developed, and the reaction is usually carried out using a full equivalent of palladium(II) acetate. This chemistry has been used in the synthesis of quadrone (equation 2).8 With the more electrophilic palladium(II) trifluoroace-tate, methyl enol ethers underwent this cyclization process (equation 3).9... 

QCdmJpFJ [QCpmJBr PdCl2 Pd(OAc)2 NaOAc 30 °C. Ligand-free, ultrasound promoted arylation of alkenes and alkynes with aryliodides palladium bis-carbenes and palladium nanoparticles ( 1 nm) are identified after catalysis product extracted with ethyl acetate/petrol ether. [66]... 

Many examples of alkene and alkyne insertion into metal-carbon bonds can also be found in the section on homogeneous catalysis. Other recent examples include the insertion of conjugated dienes into palladium-allyl bonds, olefin arylation in the presence of palladium acetate, and the reaction of ethylene with arylmagnesium halides in the presence of nickel chloride. Reaction of isocyanates with nickel-ethynyl compounds... 

The addition of several trialkyl or triarylindium reagents to the acetates of MBH adducts proceeds readily under the catalysis of copper and palladium derivatives. The reactions of trialkylindiums are catalyzed efficiently by Cul whereas additions of triarylindiums produce better results with Pd(PPh3)4. The reactions with 3-acetoxy-2-methylenealkanoates provide ( )-alkenes 213,... 

Carbonyl Compounds by Oxidation of Alcohols and Aldehydes. Salts of palladium, in particular PdCl2 in the presence of a base, catalyze the CCI4 oxidation of alcohols to aldehydes and ketones. Allylic alcohols carrying a terminal double bond are transformed to 4,4,4-trichloro ketones at 110 °C, but yield halo-hydrins at 40 °C. These can be transformed to the corresponding trichloro ketones under catalysis of palladium acetate (eq 56). The latter transformation could be useful for the formation of ketones from internal alkenes provided the halohydrin formation is regioselective. 

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