Key elements of the experimental design are depicted in Scheme [3] . Where relevant, a spirodiepoxide (II) should be polarizable at the more substituted terminus under the action of a Brønsted or Lewis acid, and the corresponding carbocation should form upon full ionization (not shown). Substrates with a suitably disposable group (X) adjacent to this site would spontaneously jettison the group and thus form a double bond (III). This process could be stepwise or concerted. Aryl- ...
