Putala, Martin and Kastner-Pustet, Nikola and Mannschreck, Albrecht (2002) Diastereoselective reaction of (MP)-pentahelicene-7,8-dione with trans-cyclohexane-1,2-diamine. Thermal and photochemical transformations of its product. TETRAHEDRON-ASYMMETRY, 12 (24): PII S0957-. pp. 3333-3342. ISSN 0957-4166
Full text not available from this repository.Abstract
The reaction of the title compounds and the transformations of the product, 3 were investigated with an emphasis on the stereochemistry. The primary interaction of the title compounds is feebly stereoselective. The diastereoisomers of product 3 exhibit free energies differing by ca. 16 kJ/mol, diastereoisomerization by helix inversion takes place during the reaction. The most stable diastereoisomers of the intermediate 8 and the product 3 show opposite helicities, which allows isolation of the product 3 in diastereoisomeric ratios from 19:81 to >99:1 depending on solvent and temperature. The free energies of activation for helix inversions of 3 were determined by time-dependent H-1 NMR. The predicted configuration of the more stable diastereoisomer of 3 was confirmed by chemical correlation to be (M,R,R). The four stereoisomers of 3 were separated by analytical enantioselective HPLC and characterized by on-line circular dichroism. Irradiation of 3 afforded the 2-substituted benzimidazole derivative 9. (C) 2002 Elsevier Science Ltd. All rights reserved.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | HELICAL PHENANTHRENES; SYSTEM; |
| Subjects: | 500 Science > 540 Chemistry & allied sciences |
| Divisions: | Chemistry and Pharmacy > Institut für Organische Chemie > Alumni or Retired Professors > Prof.Dr. Mannschreck |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 15 Nov 2021 09:45 |
| Last Modified: | 15 Nov 2021 09:45 |
| URI: | https://pred.uni-regensburg.de/id/eprint/40668 |
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