1609561-98-9Relevant academic research and scientific papers
Intramolecular reactions of metal carbenoids with allylic ethers: Is a free ylide involved in every case?
Clark, J. Stephen,Hansen, K. Emelie
, p. 5454 - 5459 (2014/05/20)
Rhodium-, copper- and iridium-catalyzed reactions of the 13C-labelled diazo carbonyl substrates 18* and 19* were performed. Results obtained from copper- and iridium-catalyzed reactions of the 13C-labelled α-diazo β-keto ester 19* indicate that either or both of these reactions do not proceed via a free oxonium ylide but instead follow a competing non-ylide route that delivers apparent [2,3]-sigmatropic rearrangement products. In the case of the iridium-catalyzed reaction of α-diazo β-keto ester 19*, results obtained from crossover experiments indicate that the initially formed metal-bound ylide dissociates to give an iridium enolate and an allyl cation, which recombine to form the C-C bond. Differing distributions of 13C-labelled rearrangement products in the rhodium-, copper- and iridium-catalyzed reactions of a 13C-labelled α-diazo β-keto ester (see scheme, DCE=dichloroethane, acac=acetylacetonate, COD=1,5-cyclooctadiene) revealed that the copper- and iridium-mediated reactions do not proceed via a common free oxonium ylide intermediate.
