Carbonyl compounds aldehyde oxidations, palladium acetate

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. 

Some synthetic modification for Pd(II)-catalyzed oxidation of silyl enol ethers is also developed. Silyl enol ethers prepared from aldehydes and ketones are converted to the corresponding a,/3-unsaturated carbonyl compound in good yields by 10 mol % of palladium(II) acetate in the presence of 1 atm pressure of O2 in DMSO as solvent (Scheme... 

Addition of tributylstannyl-lithium to crotonaldehyde and protection of the resulting alcohol with chloromethyl methyl ether gives the stannane (192), which reacts with both alkyl and aryl aldehydes RCHO to form specifically the t/rr o-hydroxy-enol ethers (193). These latter compounds have been used to prepare tra/i5-4,5-disubstituted butyrolactones by hydrolysis and subsequent oxidation. Palladium-catalysed carbonylation of RX in the presence of organotin species constitutes a useful synthesis of unsymmetrical ketones, and in the example reported this year RX is an arenediazonium salt. The reaction, which is basically an aromatic acylation, proceeds in good to excellent yield. Another Pd-catalysed reaction of aromatics, this time aryl bromides, is their reaction with acetonyltributyltin (194), prepared from methoxytributyltin and isopropenyl acetate, to give the arylacetones (195). ... 

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