Pinacol Cross‐Coupling Promoted by an Aluminyl Anion

O'Reilly, Andrea; Evans, Matthew J.; McMullin, Claire L.; Fulton, J. Robin; Coles, Martyn P.

doi:10.1002/chem.202302999

Cited by 3 publications

(5 citation statements)

References 75 publications

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“…Thus, we speculate that the ketyl radical might also exist in the reaction mixture as either a zinc or potassium complex; unfortunately, no such species could be identified. Most of the previous examples of metal-promoted 9-fluorenone ketyl generation or pinacol coupling have focused on main group metals (Mg, Ca, , and Al) and lanthanides. , For example, the reaction of magnesium(I) dimer [{( Mes Nacnac)Mg} 2 ] ( Mes Nacnac = [HC(MeCNMes) 2 ] − , Mes = mesityl) with 9-fluorenone produced magnesium fluorenone ketyl [{( Mes Nacnac)Mg(μ-9-fluorenone • )} 2 ]. In this complex, two ketyl groups bridge two Mg centers, and no C–C coupling occurred .…”

Section: Resultsmentioning

confidence: 99%

“…In this complex, two ketyl groups bridge two Mg centers, and no C–C coupling occurred . The aluminyl anion K[Al(NON)] ([NON] 2– = [O(SiMe 2 NDipp) 2 ] 2– ) can promote the reductive homocoupling of two 9-fluorenones to afford the pinacolate product [K(Et 2 O) 2 ][Al(NON){κO,O′-(O-Flu) 2 }] (Flu = 9-fluorene) …”

Section: Resultsmentioning

confidence: 99%

“…18,19 The Al(I) species showed diverse reactivity toward different ketones and aldehydes, including homocoupling (to form pinacolates) and other reductive coupling reactions 20,21 as well as cross-coupling to yield unsymmetrical pinacolate derivatives. 22 The digallane [(dpp-Bian 2− )Ga−Ga(dpp-Bian 2− )] (Bian = bis(imino-acenaphthene)) featuring Ga(II) centers can also promote pinacol coupling of benzaldehyde Ph(H)CO to yield a gallium pinacolate. 23 In recent years, our group has been exploring the reactivity of α-diimine-stabilized metal−metal-bonded compounds.…”

Section: ■ Introductionmentioning

confidence: 99%

“…14,15 . 22 The bis-chelating [Zn(R 2 CO−COR 2 ) 2 ] 2− fragment in 5 resembles the central core in 2 and 3. However, there is only one K + ion at each side of the Zn center, which is coordinated to the pinacolates and is solvated by two THF molecules.…”

Section: ■ Introductionmentioning

confidence: 99%

“…In this respect, metal–metal-bonded compounds and related mononuclear complexes bearing low-valent metal centers should be suitable reducing agents for generating ketyl radicals. For example, the reactions of β-diketiminate-stabilized Mg(I) dimers with ketones afforded a series of magnesium ketyls and their homo- or hetero- C–C coupled products. , The Al(I) species showed diverse reactivity toward different ketones and aldehydes, including homocoupling (to form pinacolates) and other reductive coupling reactions , as well as cross-coupling to yield unsymmetrical pinacolate derivatives . The digallane [(dpp-Bian 2– )Ga–Ga(dpp-Bian 2– )] (Bian = bis(imino-acenaphthene)) featuring Ga(II) centers can also promote pinacol coupling of benzaldehyde Ph(H)CO to yield a gallium pinacolate …”

Section: Introductionmentioning

confidence: 99%

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Reduction of Ketones and Coupling of Ketyls by a Zn–Zn-Bonded Compound

Liu,

Qu,

Sun

et al. 2024

Inorg. Chem.

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The α-diimine-ligated Zn−Zn-bonded compound [K(THF) 2 ] 2 [LZn−ZnL] (1, L = [(2, ) displays diverse reactivities toward a variety of ketones. In the reaction of 1 with benzophenone or 4,4′-di-tert-butylbenzophenone, a multielectron transfer process was observed to give bimetallic (Zn/K) complexes with both ketyl radical fragments and C−C coupled pinacolate moieties (products 2 and 3). In contrast, treating 1 with 9-fluorenone only afforded pinacolate complex 5. Moreover, the reactions of 1 with N-or O-heterocycle-functionalized ketones, i.e., di(2-pyridyl)ketone, 2,2-pyrrolidinone, 9xanthenone, or 10-methyl-9(10H)-acridone, were also carried out. Besides different transformations of the ketone moiety, the heteroatoms (nitrogen or oxygen) are also involved in coordination with zinc or potassium ions, yielding discrete aggregates or polymeric structures of products 6−9.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reduction of Ketones and Coupling of Ketyls by a Zn–Zn-Bonded Compound

Liu,

Qu,

Sun

et al. 2024

Inorg. Chem.

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Aluminyl Anions

Coles

2024

Encyclopedia of Inorganic and Bioinorganic Chemistry

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In 2018, a new class of low‐valent aluminum compound was introduced to the chemical literature. Aluminyl anions [Al (I) (L 2 )] − consist of an Al(I) center supported by a range of (predominantly chelating) dianionic ligand scaffolds, [L 2 ] 2− . The resulting negative charge is balanced by a group 1 metal cation with examples spanning all of the stable alkali metals Li, Na, K, Rb, and Cs. The nature and extent of cation···anion interactions can be controlled, affording three distinct structural types classified as a contacted dimeric pair (CDP), a monomeric ion pair (MIP), or a separated ion pair (SIP). The chemistry of these systems has proven to be very diverse, primarily driven by the oxidation of the aluminum to a more stable Al(III) center. Researchers have been able to harness this thermodynamically favored process to promote a number of different reactions. This article describes the oxidative addition reactions of X–Y sigma bonds to aluminyl anions, to form the corresponding aluminate products [Al (III) (L 2 )(X)(Y)] − , containing examples of new (AlH, AlB, AlC, AlN, AlO, AlF, AlSi, and AlP) bonds. The oxidation of aluminyl anions has been expanded to access compounds with new aluminum–element multiple bonds including examples of AlCR 2 ‐, AlO‐, AlS‐, AlSe‐, AlTe‐, and AlNR‐containing compounds. These terminal bonds react via [2+2] cycloaddition with unsaturated substrates to form new products, demonstrating a preference to react through formally double AlX bonds. Finally, a brief description of the application of aluminyl anions for the reductive coupling of small molecules is included. Examples involving the homocoupling of P 4 ; the homologation of CO; and the dimerization of ketones, isocyanides, and diazomethane are provided. Under favorable conditions, these couplings have been recently extended to include examples of heterocoupling of substrates, demonstrating a high degree of control of product formation.

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Alumanyl Reduction, Reductive Coupling and C–H Isomerization of Organic Nitriles

Shere,

Liu,

Hill

et al. 2024

Organometallics

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The behavior of the potassium alumanyl, [{SiN Dipp }AlK] 2 ({SiN Dipp } = {CH 2 SiMe 2 N(Dipp)} 2 ; Dipp = 2,6-i-Pr 2 C 6 H 3 ), toward organic nitriles has been investigated. In common with earlier studies of the reactivity of charge neutral Al(I) species with multiply bonded small molecules, it is suggested that the initial step in all the reactions involves [2 + 1] cycloaddition and the generation of an [η 2 −C�N−Al] alumina azacyclopropane unit. In the cases of o-and m-tolyl-substituted aryl nitriles, this species is too kinetically labile to allow its isolation and undergoes C−C coupling via immediate Al−C/C�N insertion to yield the alumina diazabutadiene derivatives. In contrast, the increased steric profile of alkyl nitriles imposes a marked influence on the nature of the products formed. Consistent with the proposed sequential pathway, reaction of [{SiN Dipp }AlK] 2 with t-BuCN provides an isolable alumina cyclopropane species that is kinetically resistant to onward reaction with a further nitrile equivalent. While reduction in the alkyl nitrile steric demands by use of i-PrCN again facilitates C−C bond formation, the crowding of the Al center by the resultant alumina-diazabutadienediide moiety appears to be beyond the limit of kinetic viability, resulting in an unusual 2-fold C−H to N−H isomerization from one of the C-iso-propyl substituents and the isolation of a 1-alumina-2,5-diazabutadiene structure.

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Pinacol Cross‐Coupling Promoted by an Aluminyl Anion

Cited by 3 publications

References 75 publications

Reduction of Ketones and Coupling of Ketyls by a Zn–Zn-Bonded Compound

Reduction of Ketones and Coupling of Ketyls by a Zn–Zn-Bonded Compound

Aluminyl Anions

Alumanyl Reduction, Reductive Coupling and C–H Isomerization of Organic Nitriles

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