- Nickel-Catalyzed Cyclopropanation with NMe4OTf and nBuLi
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Nickel was identified as a catalyst for the cyclopropanation of unactivated olefins by using in situ generated lithiomethyl trimethylammonium triflate as a methylene donor. A mechanistic hypothesis is proposed in which the generation of a reactive nickel carbene explains several interesting observations. Additionally, our findings shed light on a report by Franzen and Wittig published in 1960 that had been retracted later owing to irreproducibility, and provide a rational basis for the systematic development of the reaction for preparative purposes as an alternative to diazomethane or Simmons-Smith conditions.
- Künzi, Stefan A.,Sarria Toro, Juan Manuel,Den Hartog, Tim,Chen, Peter
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supporting information
p. 10670 - 10674
(2015/09/02)
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- SYNTHESIS AND THERMAL TRANSFORMATIONS OF BICYCLOALKENES CONTAINING A METHYLENECYCLOPROPANE FRAGMENT
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The previously undescribed 8-methylenebicyclooct-2-ene (II) and 9-methylenebicyclonon-4-ene (IV) were synthesized by the dehydrohalogenation of 8-methyl-8-chlorobicyclooct-2-ene and 9-methyl-9-chlorobicyclonon-4-ene.It was established that the hydrocarbon (II) is thermally labile, whereas the hydrocarbon (IV) does not change right up to 300 deg C.The thermal transformations of the hydrocarbon (II) and its isomeric bicyclonona-1,6-diene (III) at 100 - 180 deg C were investigated.At 100 deg C a pseudoequilibrium is established between these hydrocarbons.The final and only products from the transformations of both hydrocarbons at 180 deg C are the previously unknown anti-Bredt hydrocarbon bicyclonona-2,7-diene (XXVIIIb) and 3-methylene-1,4-cyclooctadiene (XXV), formed in a ratio of 1 : 2.5.
- Mil'vitskaya, E. M.,Pekhk, T. I.,Pereslegina, N. S.,Tarakanova, A. V.,Ivanov, A. V.
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p. 1573 - 1583
(2007/10/02)
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