1. Reactions of diazo compounds with alkenes catalysed by [RuCl(cod)(Cp)]: effect of the substituents in the formation of cyclopropanation or metathesis products
- Author
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Gabriella Buscemi, Andrea Biffis, Franco Benetollo, Cristina Tubaro, Alessandro Del Zotto, Filippo Lighezzolo, Marco Bonato, Pamela Lunardi, Chiara Vianini, and Marino Basato
- Subjects
chemistry.chemical_classification ,Double bond ,Cyclopropanation ,Stereochemistry ,diazo compounds ,Organic Chemistry ,cyclopropanation ,General Chemistry ,Metathesis ,Medicinal chemistry ,Catalysis ,Coupling reaction ,chemistry.chemical_compound ,Ethyl diazoacetate ,chemistry ,Cyclopentadienyl complex ,Diazo ,Reactivity (chemistry) ,metathesis ,ruthenium - Abstract
The reaction of diazo compounds with alkenes catalysed by complex [RuCl(cod)(Cp)] (cod = 1,5-cyclooctadiene, Cp = cyclopentadienyl) has been studied. The catalytic cycle involves in the first step the decomposition of the diazo derivative to afford the reactive [RuCl(Cp){=C(R(1))R(2)}] intermediate and a mechanism is proposed for this step based on a kinetic study of the simple coupling reaction of ethyl diazoacetate. The evolution of the Ru-carbene intermediate in the presence of alkenes depends on the nature of the substituents at both the diazo N(2)=C(R(1))R(2) (R(1), R(2) = Ph, H; Ph, CO(2)Me; Ph, Ph; C(R(1))R(2) = fluorene) and the olefin substrates R(3)(H)C=C(H)R(4) (R(3), R(4) = CO(2)Et, CO(2)Et; Ph, Ph; Ph, Me; Ph, H; Me, Br; Me, CN; Ph, CN; H, CN; CN, CN). A remarkable reactivity of the complex was recorded, especially towards unstable aryldiazo compounds and electron-poor olefins. The results obtained indicate that either cyclopropanation or metathesis products can be formed: the first products are favoured by the presence of a cyano substituent at the double bond and the second ones by a phenyl.
- Published
- 2008