Synthesis of Enantiomerically Pure Oxa[9]helicene Derivatives by a Nucleophilic Cyclodehydration Reaction of Helical 1,1′-Bibenzo[c]phenanthrenylidene-2,2′-dione
| Autor: | Michinori Karikomi, Ken-ichi Iimura, Mohammad Shahabuddin, Mohammad Salim, Md. Sharif Hossain, Mahmuda Akter |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Synlett. 33:277-282 |
| ISSN: | 1437-2096 0936-5214 |
| DOI: | 10.1055/a-1684-0448 |
| Popis: | Enantiomerically pure 9-substituted 11-oxa[9]helicene derivatives have been synthesized through furan-ring formation by a nucleophilic cyclodehydration reaction of enantiomerically pure helical polycondensed 2,2′-diphenoquinone derivatives (1,1′-bibenzo[c]phenanthrenylidene-2,2′-diones). (P)-2,2′-diphenoquinone derivatives afforded (P)-oxa[9]helicenes, whereas (M)-2,2′-diphenoquinone derivatives afforded the corresponding (M)-oxa[9]helicenes. Therefore, the ring-closing reaction afforded the corresponding enantiomerically pure products without decreasing the enantiomeric excess, and it proceeded stereospecifically with retention of the configuration. The thermal stability of an oxa[9]helicene was studied by determining the decrease in its enantiomeric excess at various temperatures, and its racemization barrier was found to be 165.6 kJ/mol. |
| Databáze: | OpenAIRE |
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