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Abstract
A keystone methodology in synthetic chemistry, metalation
(metal-hydrogen exchange) reactions of aromatic compounds
are usually the domain of highly reactive polar
organometallics such as alkyllithium compounds, LICKOR
(alkyllithium compounds cocomplexed with potassium tertbutoxide)
superbases, or lithium amides.[1] Strictly these
reactions are lithiations (or potassiations) as the incoming
lithium atom (or potassium atom) takes the place of the
outgoing hydrogen atom. The lower-polarity metals magnesium,
zinc, and aluminum generally form slow-reacting
metalating agents which are ineffective towards aromatic
compounds. Therefore, to attach these less reactive metals
directly to an aromatic scaffold, the lithiated aromatic
compound must be synthesized beforehand and then an
additional metathetical reaction often involving a metal
halide (for example, RMgX, ZnX2, or R2AlX) has to be
carried out. The presence of the ionic halide often limits the
range of solvents available for such reactions with hydrocarbons
and arenes, which are generally ruled out in favor of
polar substitutes (commonly ether or THF). Recently, however,
it has been shown that pairing lithium (or another alkali
metal) with one of these inferior multivalent metals in the
same organometallic molecule (an '-ate' formulation), can
generate 'synergic', mixed-metal reagents capable of directly
magnesiating,[2,3] zincating,[3] or aluminating[4] aromatic substrates,
thus circumventing the need for a subsequent metathesis.
In addition to this new inorganic (metal) perspective,
these synergic reagents can open up new organic horizons by
promoting unusual regioselective deprotonations (for example,
meta-orientated in the cases of toluene[5] and N,Ndimethylaniline[
6]) or special polydeprotonations (for example,
2,6-twofold in the case of naphthalene[7] and 1,1',3,3'-
fourfold in the cases of ferrocene and its Group 8 homologues[
8]).
Original language | English |
---|---|
Pages (from-to) | 1105-1108 |
Number of pages | 3 |
Journal | Angewandte Chemie |
Volume | 46 |
Issue number | 7 |
DOIs | |
Publication status | Published - 5 Feb 2007 |
Keywords
- alkali metals
- ferrocenes
- lithium
- manganese
- metalation
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Dive into the research topics of 'Alkali-metal-mediated manganation: a method for directly attaching manganese(II) centers to aromatic frameworks'. Together they form a unique fingerprint.Projects
- 2 Finished
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"INVERSE" COORDINATION: A NEW DESIGN CONCEPT IN SUPRAMOLECULAR INORGANIC CHEMISTRY
Mulvey, R. (Principal Investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/10/06 → 31/03/10
Project: Research
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Mixed-Metal Molecular Synergy and its Application in Inverse Crown Chemistry
Mulvey, R. (Principal Investigator)
EPSRC (Engineering and Physical Sciences Research Council)
1/01/05 → 31/01/09
Project: Research