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Gold Carbenoids: Lessons Learnt from a Transmetalation Approach
Author(s) -
Seidel Günter,
Gabor Barbara,
Goddard Richard,
Heggen Berit,
Thiel Walter,
Fürstner Alois
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201308842
Subject(s) - transmetalation , carbenoid , carbene , bimetallic strip , chemistry , nucleophile , combinatorial chemistry , catalysis , organic chemistry , rhodium
Carbophilic catalysts that are based on Au I allow a host of different nucleophiles to be added across various π systems.1–3 Although many of these reactions are thought to proceed via gold carbenoids, the challenge to observe and characterize these putative intermediates has basically been unmet.4 The current mechanistic interpretation therefore largely relies on indirect evidence and computational data, some of which are subject to debate.5 In an attempt to fill this gap, we pursued a potential route to gold carbenoids by formal transmetalation of chromium or tungsten Fischer carbene complexes with [LAu] + . Whereas this transformation proceeds with exceptional ease as long as a stabilizing heteroelement is present on the carbene center, it stops half‐way in its absence. Rather unusual bimetallic arrays are formed, which allow the charge density to delocalize over several positions. The obvious difficulty of releasing an “unstabilized” gold carbenoid has potential mechanistic implications for the understanding of π‐acid catalysis in general.