Lead tetraacetate reaction with dicarboxylic acids

Dicarboxylic acids undergo to-decarboxylation on reaction with lead tetraacetate to give alkenes. This reaction has been of occasional use for the synthesis of strained alkenes. 

Reactions of 4,7-phenanthroline-5,6-dione have been the subject of considerable study. It is reduced to 5,6-dihydroxy-4,7-phenanthroline by Raney nickel hydrogenation226,249 or by aromatic thiols in benzene,262 and oxidized by permanganate to 3,3 -bipyridyl-2,2 -dicarboxylic acid.263 It forms bishemiketals with alcohols226 and diepoxides with diazomethane.226 The diepoxides by reaction with hydrochloric acid form diols of type 57, R = Cl, which on oxidation with lead tetraacetate give 3,3 -bipyridyl diketones of type 58, R = Cl. Methyl ketones of type 58, R = H, are also obtained by lead(IV) acetate oxidation of the diol 57, R = H, obtained by lithium aluminum hydride reduction of 57, R = Cl. With phenyldiazomethane and diphenyldiazomethane the dione forms 1,3-dioxole derivatives,264,265 which readily hydrolyze back to the dione with concomitant formation of benzaldehyde and benzophenone, respectively. 

Reaction of a-diketones with lead tetraacetate Dicarboxylic acid esters from cyclic a-diketones... 

The use of lead tetraacetate to carry out oxidative bisdecarboxylation of diacids has been found to be a highly useful procedure when used in conjunction with the Diels-Alder addition of maleic anhydride to dienes, the latter process providing a ready source of 1,2-dicarboxylic acids. The general pattern is illustrated in the reaction... 

Though MOM deprivation product 2.2.21 was accidentally obtained, it was still useful to test two key reactions for total synthesis Wessely oxidative dearomatization reaction and intramolecular Diels-Alder reaction (Fig. 2.20). A pair of diethyl phthalate derivative 2.2.22 with the ratio of 2 1 and 95 % yield could be obtained from phenol 2.2.21 in acetic acid solvent with the presence of lead tetraacetate at room temperature after 5 min. Then, we tried intennolecular Diels-Alder reaction. Unfoitunately, both substrate 2.2.22 and dimethyl acetylene dicarboxylate were not producing Diels-Alder product 2.2.23 under toluene refluxing or sealing mbe heating conditions, only gave the results of raw material recovery. 

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