Märkl, Gottfried and Ehrl, Robert and Kreitmeier, Peter and Burgemeister, Thomas (1998) 8,19-dimethyl-tetraepoxy[22]annulene(2.1.2.1): The first tetraepoxy-bridged aromatic [22]annulene. HELVETICA CHIMICA ACTA, 81 (1). pp. 93-108. ISSN 0018-019X, 1522-2675
Full text not available from this repository.Abstract
By McMurry reaction of 5,5'-ethylidenebis[furan-2-carbaldehyde] (15), a syn/anti mixture 16 of (E,E)- and (Z,Z)-8,19-dihydro-8,19-dimethyl-tetraepoxy[22]annulene is obtained. The (E/E)-isomers 16 are the first rotationally active noncyclic conjugated macrocycles, where the (E)-ethenediyl moieties rotate around the connecting single bonds. The dihydro-tetraepoxy[22]annulenes 16 are dehydrogenated by (Ph3C)BF4 as well as by O-2 to give the tetraepoxy[22]annulene 11. The spectroscopic data support the character of 11 as an aromatic, diatropic ring system, which is rather sensitive towards O-2. In the oxidation mixture obtained from 11, beside polymeric products, two compounds 19 and 20 can be isolated, carrying one and two CHO groups, respectively, resulting by oxidation of one or both Me-groups but having retained the aromatic 22 pi system of 11.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | COUPLING REACTIONS; DICATION; TITANIUM |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 01 Mar 2023 07:56 |
| Last Modified: | 01 Mar 2023 07:56 |
| URI: | https://pred.uni-regensburg.de/id/eprint/50208 |
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