text: In one study, seven-membered rings were constructed in a tandem 5-exo-dig addition reaction / Claisen rearrangement:
  A 6-endo-dig pattern was observed in an allene - alkyne 1,2-addition / Nazarov cyclization tandem catalysed by a gold compound:
  A 5-endo-dig ring closing reaction was part of a synthesis of (+)-Preussin: