Ring formation from acyclic precursors: sequential palladium-catalyzed double acetoxylation-cyclization of 3,6-heptadienoates to 2,4-diacetoxycyclopentylideneacetates

An efficient reaction protocol for the palladium-catalyzed synthesis of 2,4-diacetoxycyclopentylideneacetates by a reaction of acetic acid with 3,6-heptadienoic esters, has been developed. The process, which occurs in the presence of oxidants, represents the first example of sequential double acetoxylation-cyclization of substituted 1,4-dienes to form cyclopentane rings with oxygen functionalities at 2 and 4 carbon atoms. The use of a water/acetic acid reaction medium has also been shown to give satisfactory results.