The oxidation of benzylic positions to carbonyl groups is one of the most important transformations in the synthetic chemistry [1,2]. On the other hand, if the transformation of benzylic positions directly into acetals as depicted in Scheme 1 were realized, it would be also useful in organic synthesis. ... During the course of our studies aimed at synthesis of a bicyclo[2.2.2]oct-5-ene- 2,3-dione skeleton by the Diels-Alder reaction of 2,3,4,5-tetrachloro-o-benzoquinone (o- ...