Azepines

Azepines are seven-membered heterocyclic compounds important in medicinal chemistry and drug design for CNS and therapeutic agents.

Structure

• These are seven-membered heterocycles with one nitrogen atom.
• Can be saturated or unsaturated (aromatic).

• There are several subclasses:
  • Azepine (basic)
  • Diazepine (2 N atoms – as in benzodiazepines)
  • Thiazepine (N and S atoms)

Synthesis of Azepines

1. Ring Expansion

   • From six-membered rings (like cyclohexanones or pyridines) via:
     • Rearrangement reactions
     • Radical cyclization
     • Photochemical methods

2. Cyclization Reactions

   • Nucleophilic amines with dihaloalkanes.
   • Grignard or Wittig reactions to close the ring.

3. Fischer Indole Reaction Variant

   • Used to synthesize diazepines and related systems.

Medicinal Uses of Azepines and Derivatives

1. Benzodiazepines (e.g., diazepam, lorazepam):
   • Act on GABA-A receptors, CNS depressants.
   • Used as anxiolytics, sedatives, anticonvulsants.
2. Thiazepines:
   • Quetiapine – antipsychotic, used in schizophrenia.
   • Zotepine – similar mechanism.
3. Oxazepines:
   • Carbamazepine – anticonvulsant, mood stabilizer.

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