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Attempts Directed towards the Synthesis of Intermediate (Aryne)chromium Complexes from Aryl Triflates and from (Haloarene)chromium Complexes
Author(s) -
Werner Georg,
Butenschön Holger
Publication year - 2012
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201200176
Subject(s) - chemistry , trifluoromethanesulfonate , aryne , chromium , aryl , medicinal chemistry , ligand (biochemistry) , reactive intermediate , homoleptic , fluoride , stereochemistry , organic chemistry , catalysis , inorganic chemistry , metal , biochemistry , alkyl , receptor
The generation of (η 6 ‐aryne)chromium complexes as reactive intermediates was investigated in two ways. Although earlier attempts directed towards triflate eliminations from a variety of tricarbonyl(phenyl triflate)chromium complexes had failed, more electron‐rich phenyl triflate complexes were considered. This was accomplished either by substitution with two methoxy groups in the arene ligand or by replacement of one of the three carbonyl ligands of the tricarbonylchromium complex with triphenylphosphane. However, the attempted elimination still did not take place; in spite of the increased electron densities in the aromatic ligands, anionic thia‐Fries rearrangements were observed in high yields at –78 °C. As an alternative, elimination of lithium fluoride was tested. Tricarbonyl(2‐lithiofluorobenzene)chromium(0) was generated by tin/lithium exchange. After hydrolytic workup, tricarbonyl(fluorobenzene)chromium was obtained as the main product, indicating that the lithiation step had been successful. A dimeric side product provided evidence for the intermediacy of (benzyne)tricarbonylchromium.