Plumbates synthesis

The procedure described here serves to illustrate a new, general method for effecting the < -arylation of g-dicarbonyl compounds by means of an aryllead triacetate under very mild conditions. Although the first synthesis of an aryllead triacetate was reported relatively recently, a wide range of these compounds can now be readily prepared. The most direct route to these compounds is plumbation of an aromatic compound with lead tetraacetate, and in the procedure reported here p-methoxyphenyllead triacetate has been prepared in this way. It may also be obtained by reaction of the diarylmercury with lead tetraacetate, a longer, but more general method of synthesis of aryllead triacetates. 

The first synthesis of p-methoxyphenyllead triacetate by direct plumbation was reported by Harvey and Morman, who obtained the compound in 2418 yield by heating anisole and lead tetraacetate in acetic acid at SO C for 4... 

Lead dioxide is widely used as an oxidizing agent in the arts as well as in the laboratory. It reacts with strong bases with the formation of plumbates, M2Pb03 and dissolves in strong acids, presumably forming plumbic salts. It will not react with weaker acids, such as acetic (c/. the preparation of lead tetracetate, synthesis 17). 

The synthesis of aryllead triacetates has been well developed over the past 40 years [79]. There are two principle methods for the synthesis of aryllead triacetates direct plumbation and transmetallation. The simplest method is direct plumbation where an arene can be reacted directly with Pb(OAc>4 to form an aryllead triacetate by a highly selective electrophilic aromatic substitution reaction. Pb(OAc>4 can be reacted with 1,3,5-trimethoxybenzene (138) in CHCI3 at room temperature to generate 2,4,6-trimethoxyphenyllead triacetate (139) in 76 % yield (Scheme 4.35). Although this method is limited to electron rich arenes it is a remarkably selective reaction. 

Scheme 4.35 Synthesis of 2,4,6-trimethoxyphenyllead triacetate by direct plumbation...

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