Wessely acetoxylation

When the reactions of phenols with aryllead triacetates were performed in the presence of pyridine, only the C-arylated dienones were formed in a nearly quantitative yield (90% ratio ortho para = 4 1). Under the classical conditions (phenol organolead triacetate base in a ratio 1 1 3), the reaction of methylated phenols only proceeds in high yield when both ortho positions are substituted. There is a preference for attack ipso to a methoxyl group compared to a methyl group. As in the Wessely acetoxylation, there is a marked preference for orr/io-arylation. 

The middle game involves the conversion of a hydroxyalkyl-substituted phenol (Scheme 40) to diastereoisomeric Cig-cyclohexadienones (Scheme 41) by Wessely acetoxylation. These are subjected to UV irradiation to give... 

Oxidative nucleophilic substitution is, however, a more versatile technique and a much better choice for target-oriented synthesis (Sections 15.1.1 and 15.1.2.2). In 1950, Wessely and co-workers examined the use of lead tetraacetate (LTA) in acetic acid to determine the structure of phenols and, in doing so, they developed their oxidative acetoxylation reaction, referred to herein as Wessely oxidation (Figure 13) [68-76]. If both an ortho- and a para-position are available to accommodate the entry of the acetoxy nucleophile, ortho products often predominate even when the ortho position is already occupied by a resident alkyl (e.g. 40 —> 41a/b) or allcoxy group (Figure 13) [69, 74]. 

The convenient generation of bicyclo[2.2.2]octenones through the use of ortho-quinol derivatives in Diels-Alder reactions recently inspired Wood and co-workers in their studies toward the total synthesis of CP-263,114 (110) [148]. They relied on the Wessely-Yates tandem oxidative acetoxylation/intramolecular Diels-Alder sequence to build bicyclo[2.2.2]octenones such as 114 en route to advanced isotwistane intermediates such as 111b, which could eventually be fragmented to furnish the carbocyclic core of 110 (i.e. 111a —> 110, Figure 29) [149-153],... 

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