atom must be such that the centers H-C@)-C(a)-C-0-0 in the hydroxy-hydroperoxy diradical can assume a cyclic arrangement. Table 3 shows a number of cases studied so far, in which a cyclic ketone is converted to an unsaturated carboxylic acid containing an additional oxygen atom. With the exception of (62), all the ketones contain a CH3-substituent a to the carbonyl group. In these examples the new C=C double bond, which is formed together with the carboxyl group, is always terminal.
Scope of the ReactionConsequently, this new photo-oxidation can be used as a step in the partial synthesis of 3,4-seco-triterpenecarboxylic acids with a A4 (23)