text:  Research involving the reaction was relatively quiet in subsequent years , until in the mid @-@ 1980s when several syntheses employing the Nazarov cyclization were published . Shown below are key steps in the syntheses of Trichodiene and Nor @-@ Sterepolide , the latter of which is thought to proceed via an unusual alkyne @-@ allene isomerization that generates the divinyl ketone . 
  