Calcium-mediated fulvene couplings. 3. Reductive coupling of guaiazulene with activated calcium to give a mixture of 8,6′ and 8,8′ (diguaiazulenide)calcium isomers. Thermal rearrangement of the 8,6′ isomer to the 8,8′ isomer and X-ray crystal structure of the 8,8′ isomer
| Autor: | Britta Höhn, Piet-Jan Sinnema, Brendan Twamley, Pamela J. Shapiro |
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| Rok vydání: | 2003 |
| Předmět: |
Organic Chemistry
X-ray chemistry.chemical_element Recrystallization (metallurgy) Crystal structure Calcium Photochemistry Biochemistry Medicinal chemistry Inorganic Chemistry chemistry.chemical_compound chemistry Guaiazulene Materials Chemistry Physical and Theoretical Chemistry Selectivity Tetrahydrofuran Fulvene |
| Zdroj: | Journal of Organometallic Chemistry. 676:73-79 |
| ISSN: | 0022-328X |
| DOI: | 10.1016/s0022-328x(03)00310-3 |
| Popis: | The reductive coupling of guaiazulene with activated calcium in THF at 30–35 °C affords a 60:40 mixture of two isomers, 8,8′-(1) and 8,6′-(2) (diguaiazulenide)bis(tetrahydrofuran)calcium, respectively, in nearly quantitative yield. The isomers were separated and purified by recrystallization. The X-ray crystal structure of 1 is reported. A modest dependence of the isomer ratio on the reaction temperature was noticed. At lower temperature (9 °C) the 8,6′ isomer, 2, is favored slightly, and at higher temperature (67 °C) selectivity for the 8,8′ isomer, 1, is slightly enhanced. Thermolyses of each isomer revealed that 1 is the thermodynamically preferred isomer. |
| Databáze: | OpenAIRE |
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