Synthesis of bis(enolnonaflates) and their 4-exo-trig-cyclizations by intramolecular Heck reactions

Starting from dimedone, novel 1,3-bis(enolnonaflates) (nonafluorobutanesulf onates) have been prepared in four efficient steps. Cyclization of these 1, 5-hexadienes under Palladium catalysis proceeded cleanly to give bicyclo[4. 2.0]octadienes and bicyclo[4.2.0]octenones, respectively, by an unprecedent ed 4-exo-trig process. Insertion in one enolsulfonate moiety, intramolecula r cyclization and subsequent second insertion after intermolecular reaction with alkenes (acrylates) or alkynes (3,3-dimethylbutyne) led to novel, hig hly congested hydrocarbons. Application of a chiral catalyst system resulte d in modest asymmetric induction to furnish an enantioselective Heck-type d esymmetrization reaction product.