Ruthenium-Catalyzed [2+2+2] Bis-Homo-Diels-Alder Cycloadditions of 1,5-Cyclooctadiene with Alkynyl Phosphonates

The ruthenium-catalyzed [2+2+2] bis-homo-Diels-Alder cycloaddition between 1,5-cyclooctadiene and alkynyl phosphonates was investigated. Various alkynyl phosphonate moieties were found to be compatible with the cycloaddition to give the tricyclo[4.2.2.0(2,5)]dec-7-enetricyclic compounds in yields of 46-97%.