Arenes plumbylation

Lead(IV) acetate is most commonly employed to plumbylate arenes, often using chloroform as the solvent. Being a relatively weak electrophile, Pb(OAc)4 can react only with electron-rich aromatic compounds, for example anisole and polyalkoxy-benzenes. The electrophilicty of the lead reagent is, however, enhanced substan-... 

Lead(IV) trifluoroacetate in TFAH is a very reactive electrophile that is capable of plumbylating less electron-rich arenes. Nonetheless, the use of trifluoroacetate anions in the plumbylation reactions should be avoided, because aryllead(IV) tri-fluoroacetates are unstable compounds that readily decompose to the corresponding aryl trifluoroacetates and biaryls [34—37, 40, 41]. It has been reported [41] that 4-FC6H4ArPb(TFA)3 is reasonably stable and can be isolated from the reaction of Pb(TFA)4/TFAH with fluorobenzene. A mechanistic study [41] indicated an electrophilic substitution path for the plumbylation reaction, which seemed to be substantially more para-selective than mercuration and thallation. For example, the plumbylation of toluene with Pb(OAc)4 in dichloroacetic acid has been reported [41] to occur with >90 % para-selectivity. 

The aryllead(IV) tricarboxylates can be prepared, among several possible routes, the most conveniently by the reaction of aryltri-n-butylstannanes [66], or arylboronic acids [67] with lead(IV) acetate in the presence of mercury(II) trifluoroacetate as the catalyst, or, in the case of electron-rich arenes such as polyalkoxybenzenes, by direct plumbylation with Pb(OAc)4 or its derivatives. Scheme 32. 

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