Thia Enediynes, Monocyclic or Fused with Arenes Through the Double Bond

and Thia Enediynes, Monocyclic or Fused with Arenes Through the Double Bond 

4 Cyclic Enediynes Fused with Other Rings Through Carbons 7-10 

The fusion of a 10-membered cyclic enediyne with another ring is expected to stabilize it against cycloaromatization provided that  

As far as this latter point is concerned, there is evidence that 6- or 7-membered rings are too large to function as blocking devices. On the other hand, fusion with 3-membered rings has not yet been explored. So, the most useful cases regard 5- or 4-membered rings. 

Also fusion of a p-lactam involving the nitrogen atom and C-4 was explored.The resulting bicyclic azaenediynes are also stabilized toward cycloaromatization. However, they are somehow less stable in the dry state, and are therefore less useful. 

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