Lead (IV) acetate oxidation of unsaturated carboxylic acids, esters and amides. The mechanism of the reaction

✍ Scribed by Robert M. Moriarty; Harold G. Walsh; Harsh Gopal

• Publisher: Elsevier Science
• Year: 1966
• Tongue: French
• Weight: 190 KB
• Volume: 7
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)76065-5

✦ Synopsis

Lead tetraacetate oxidation of saturated carboxylic acids causes decarboxylatioq with formation of the corresponding lower acetate and alkene' . Koch1 *2 has presented excellent evidence in support of a free rodica' chain mechanism for the oxidative decarboxylation. In the case of certain unsaturated carboxylic acids the oxidation takes a markedly different course. Instead of oxidative decarboxylation, intramolecular acetoxy lactone formation occurr3. We wish to report on the synthetic utility of this reaction as well as the mechanistic pathway by which it proceeds. Typically endo+carboxy-bicycle [2,2,j]hept-2-ene (J, upon lead tetraacetate oxidation in either benzene or pyridine, was found to yield acetoxy lactone I@' in 80% yield. Similar oxidation of A2-cyc'opentenyl acetic acid (IJI) yielded acetoxy lactone (m5 in 70% yield. Only in the oxidation of endo-5-corboxybicyclo[2,2,2]oct-2-ene 0 was substantial decarboxylation observed, and about 15% of the known M-acetoxy-6a-hydroxybicyclo [2,2,2j'octane 2a-carboxy'ic 6a-lactone (Vl)4b was obtained6.