Silaheterocyclen, XXXI [1]. Spaltung von 2-Silanorbornenen: Ein einfacher Weg zu Cyclopentenylderivaten von Organochlorsilanen und zu 2-Silanorbornanen / Silaheterocycles, XXXI [1]. Allyl Cleavage of 2-Silanorbornenes: A Facile Synthesis of Cyclopentenyl- Compounds of Organochlorosilanes and of 2-Silanorbornanes
| Autor: | Norbert Auner, Hans-Uwe Steinberger |
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| Rok vydání: | 1994 |
| Předmět: | |
| Zdroj: | Zeitschrift für Naturforschung B. 49:1743-1754 |
| ISSN: | 1865-7117 0932-0776 |
| Popis: | The exo/endo[4+2]-cycloadducts of Cl2Si=CHCH2 tBu and cyclopentadiene 1 are transformed into the Si-dimethoxy- and chloro-methyl-substituted derivatives 2 and 4. In the case of the 2-silabicyclo[2.2.1] compounds 2 (R1 = R2 = OCH3), 3 (R1 = R2 = CH3) and 4 (R1 = Cl; R2 = CH3) the allyl cleavage with HCl/ether gives the ring opened products 8, 9, and 10 in good yields. The reaction can also be carried out with HBr/ether. In 1 the cleavage of the allyl-silicon bond is disfavoured due to the two chlorine atoms at silicon. Instead HCl adds to the C=C double bond and stereospecifically gives the exo-6-chloro-2,2-dichloro-3-exo/endo-neopentyl-2-silabicyclo[2.2.1]heptanes 5. When the stronger acid CF3SO3H is used no addition to the double bond is observed but only the allyl cleavage takes place to give the triflate 7. The ring opened cyclopentene compounds can be reduced by LiAlH4 to give the corresponding Si-H-compounds 19 and 20. Intramolecular hydrosilylation of 19 leads to the exo/endo-2,2-dimethyl-3-neopentyl-2-silabicyclo[2.2.1]heptanes 21 and so the former bicyclic structure is regenerated. |
| Databáze: | OpenAIRE |
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