Synthesis and Medicinal use of Azepines: Azepines are poly-unsaturated non-aromatic seven-membered heterocyclic rings, with nitrogen replacing carbon. The increase in ring size constrains these compounds to be non-polar to lessen the ring strain. This explains their non-aromatic nature. These heterocyclics follow the reactivity pattern of cyclic polyenes. The chemistry of azepines is dominated by their polyene character.
Synthesis of Azepines
The nitrobenzene is deoxygenated using tributylphosphine. The resulting aryl nitrene undergoes ring expansion through intramolecular rearrangement in the presence of primary/secondary alcohol to give 2-alkoxy -3H-azepines.
(a) Imipramine synthesis:
(b) Carbamazepine synthesis:
Medicinal Use of Azepines
Important drugs from azepine category include imipramine (antidepressant), diazepam (tranquillizer), temocapril (ACE-inhibitor/antihypertensive), omapatrilat (anti-hypertensive), quetiapine (anti-psychotic), tianeptine (anti-depressant), etc.
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