Synthesis and structure determination of novel hexasubstituted cyclohexadienes

The linear trienes were obtained in high yields by copper-mediated cycloaddition of 2,5-bis(trimethylsilyl)zirconacyclo-pentadienes with dimethyl acetylenedicarboxylate (DMAD) which can be quantitatively converted to novel asymmetric hexasubstituted cyclohexadienes with high (E)-stereoselectivity. The structure of cyclohexadienes was determined via X-ray analysis.