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Intramolecular Reactions of Metal Carbenoids with Allylic Ethers: Is a Free Ylide Involved in Every Case?
Author(s) -
Clark J. Stephen,
Hansen K. Emelie
Publication year - 2014
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201304054
Subject(s) - ylide , diazo , iridium , oxonium ion , chemistry , intramolecular force , allylic rearrangement , rhodium , medicinal chemistry , cyclopropanation , photochemistry , catalysis , organic chemistry , ion
Rhodium‐, copper‐ and iridium‐catalyzed reactions of the 13 C‐labelled diazo carbonyl substrates 18* and 19* were performed. Results obtained from copper‐ and iridium‐catalyzed reactions of the 13 C‐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 CC bond.