Heterocyclische Siebenring-Verbindungen, XXXVI. Synthese und Eigenschaften des 1,4-Benzoxazepins und einiger monosubstituierter Derivate

✍ Scribed by Hofmann, Hans ;Fischer, Herbert

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 635 KB
• Volume: 1990
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1990199001168

✦ Synopsis

Heterocyclic Seven‐Membered Ring Compounds, XXXVI. — Synthesis and Properties of 1,4‐Benzoxazepine and of Some Monosubstituted Derivatives

O‐Alkylation of salicylamide with bromoacetaldehyde diethyl acetal and subsequent thermal ring closure yields the lactam 2, which is converted into the imide chloride 3. Pd(0)‐catalyzed dehalogenation of compound 3 with tributyltin hydride leads to the desired 1,4‐benzoxazepine (4), a thermally very unstable compound which prefers polymerization to valence isomerization. O‐Alkylation of the lactam 2 and S‐alkylation of the thiolactam 8 yield the 5‐substituted 1,4‐benzoxazepines 6 and 9, resp., which are thermally considerably more stable than the parent compound 4. Thus, they are capable of the expected thermal isomerization to the corresponding hydroxyisoquinolines 10 and 11, resp. The photoisomerization of the 1,4‐benzoxazepines 4, 6, and 9 leads to the thermally very unstable dihydroazetes 12, 13, and 14, of which only the methylthio compound 14 could be isolated as crystalline compound.