Heterocyclische und carbocyclische 12-π- and 14-π-Molekülsysteme, 47. Mitteilung. Herstellung von 7, 9-Dimethyl-4, 5-dihydro-3 H-benz [cd]- azulen-3-on and 7,9-Dimethyl-3H-benz [cd]azulen-3-on. Eine einfache Synthese eines Azulenopseudophenalenons
✍ Scribed by Richard Neidlein; Walter Kramer
- Publisher
- John Wiley and Sons
- Year
- 1982
- Tongue
- German
- Weight
- 387 KB
- Volume
- 65
- Category
- Article
- ISSN
- 0018-019X
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✦ Synopsis
Heterocyclic and Carbocyclic 12‐π‐and 14‐π‐Systems, 47th Commnunication^1^. Synthesis of 7,9‐Dimethyl‐4,5‐dihydro‐3__H__‐benz[cd]azualene‐3‐one and 7,9‐Dimethyl‐3__H__‐benz[cd]azulene‐3‐one. A Simple Synthesis of Azulenopseudophenalenons
4, 6, 8‐Trimethylazulene (3) reacts after metalation with lithiumdiisopropyl‐amide in ether with bromoacetic acid to the 6, 8‐dimethylaltulene‐4‐propionic acid (4), which undergoes cyclization to the 7, 9‐dimethyl‐4, 5‐dihydro‐3__H__‐benz [cd]‐azulene‐3‐one (5) in the presence of p‐toluenesulfonic acid; oxidation of 5 with 2, 3‐dichloro‐5, 6‐dicyanobenzoquinone yields 7, 9‐dimethyl‐3__H__‐benz [cd]azulene‐3‐‐one (1b). Alkylation of 1b with triethyloxonium tetrafluoroborate in CH~2~C1~2~ gives the 3‐ethoxy [cd]benzazulenium tetrafluoroborate (6).