Abstract:

Cyclic α,β-epoxy ketones are valuable synthetic intermediates due to their high reactivity. Various products resulting from rearrangements of cyclic 2,3- epoxy ketones are important starting materials for the synthesis of perfumes, synthetic food flavorings, and pharmaceuticals. Lewis acid catalyzed ring opening of these epoxides usually follow some well defined paths: the intermediate carbocation is always formed in the carbon atom farther from the carbonyl group (III) (Scheme 1), because this group destabilizes positive charges in -position. The carbocation can either undergo acyl migration or H+ elimination (or hydrogen migration) to form a ring-contracted aldehyde (A) or an - diketone (B) (Scheme 1). Scheme 1: Lewis acid catalyzed rearrangement of cyclic 2,3-epoxy ketones.