7-Membered Rings
With 7-membered rings, the heteroatom must be able to provide an empty pi orbital (e.g., boron) for "normal" aromatic stabilization to be available; otherwise, homoaromaticity may be possible. Compounds with one heteroatom include:
| Heteroatom | Saturated | Unsaturated |
|---|---|---|
| Nitrogen | Azepane | Azepine |
| Oxygen | Oxepane | Oxepine |
| Sulfur | Thiepane | Thiepine |
Those with two heteroatoms include:
| Heteroatom | Saturated | Unsaturated |
|---|---|---|
| Nitrogen | Homopiperazine | Diazepine |
| Nitrogen/sulfur | Thiazepine |
Read more about this topic: Heterocyclic Compound
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