Bisdecarboxylation with Lead Tetraacetate

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 

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Compounds containing carboxyl groups on adjacent carbons (succinic acid derivatives) can be bisdecarboxylated with lead tetraacetate in the presence of O2 263 jjjg reaction is of wide scope. The elimination is stereoselective, but not stereospecific (both meso- and dl- 2,3-diphenylsuccinic acid gave trans- stilbene) a concerted mechanism is thus unlikely. The following mechanism is not inconsistent with the data ... 

Compounds containing geminal carboxyl groups (disubstituted malonic acid derivatives) can also be bisdecarboxylated with lead tetraacetate, gcm-diacetates (acylals) being produced, which are easily hydrolyzable to ketones ... 

The oxidative bisdecarboxylation of a,/3-dicarboxylic acids is usually carried out with lead tetraacetate and pyridine, in benzene or acetonitrile as solvent, at 50-60° [procedure of Grob (1,554-555)]. However, these conditions are reported2 to be unsuccessful in some cases, for example with (1) (1,4-dimethoxycarbonyl-bicyclo[2.2.2]octane-2,3-dicarboxylic acid). The decarboxylation, however, is successful in refluxing benzene (45% yield)3 or can be conducted at room temperature in comparable yield if dimethyl sulfoxide or dioxane is used as solvent.4... 

Anodic dehydrogenations, e.g., oxidations of alcohols to ketones, have been treated in Sect. 8.1 and formation of olefins by anodic elimination of C02 and H+ from carboxylic acids was covered in Sect. 9.1. Therefore this section is only concerned with anodic bisdecarboxylations of v/odicarboxylic acids to olefins. This method gives usually good results when its chemical equivalent, the lead tetraacetate decarboxylation, fails. Combination of bisdecarboxylation with the Diels-Alder reaction or [2.2] -photosensitized cycloadditions provides useful synthetic sequences, since in this way the equivalent of acetylene can be introduced in cycloadditions. 

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