Aluminum Bases for the Highly Chemoselective Preparation of Aryl and Heteroaryl Aluminum Compounds

Wunderlich, Stefan H.; Knöchel, Paul

doi:10.1002/anie.200804966

Cited by 99 publications

(65 citation statements)

References 62 publications

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“…43 Closely related to this work, Knochel has demonstrated the synthesis of the Fe(II) complex [(TMP)2Fe·4LiCl·2MgCl2], capable of metallating functionalised arenes to undergo subsequent nickel-catalysed cross-couplings with alkyl halides. 44 Despite these insightful studies in organic synthesis, the structure or constitution of the proposed ferrate intermediates has not been forthcoming. In addition, Mulvey has reported structurally well-defined ferrate complex [Na4Fe2(TMP)6(C6H4)], which promote the direct diferration of benzene.…”

Section: Introductionmentioning

confidence: 99%

Synthetic, structural and magnetic implications of introducing 2,2′-dipyridylamide to sodium-ferrate complexes

et al. 2017

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This version is available at https://strathprints.strath.ac.uk/60604/ Strathprints is designed to allow users to access the research output of the University of Strathclyde. Unless otherwise explicitly stated on the manuscript, Copyright © and Moral Rights for the papers on this site are retained by the individual authors and/or other copyright owners. Please check the manuscript for details of any other licences that may have been applied. You may not engage in further distribution of the material for any profitmaking activities or any commercial gain. You may freely distribute both the url (https://strathprints.strath.ac.uk/) and the content of this paper for research or private study, educational, or not-for-profit purposes without prior permission or charge.Any correspondence concerning this service should be sent to the Strathprints administrator: strathprints@strath.ac.ukThe Strathprints institutional repository (https://strathprints.strath.ac.uk) is a digital archive of University of Strathclyde research outputs. It has been developed to disseminate open access research outputs, expose data about those outputs, and enable the management and persistent access to Strathclyde's intellectual output. Using a transamination approach to access novel Fe(II) complexes, this study presents the synthesis, X-ray crystallographic and magnetic characterisation of a series of new iron complexes containing the multifunctional 2,2-dipyridylamide (DPA) ligand using iron bis(amide) [{Fe(HMDS)2}2] and sodium ferrate [{NaFe(HMDS)3} ] (1) as precursors (HMDS = 1,1,1,3,3,3hexamethyldisilazide). Reactions of DPA(H) with 1 show exceptionally good stoichiometric control, allowing access to heteroleptic [(THF)2·NaFe(DPA)(HMDS)2] (3) and homoleptic [{THF·NaFe(DPA)3} ] (4) by using 1 and 3 equivalents of DPA(H) respectively. Linking this methodology and co-complexation, which is a more widely used approach to prepare heterobimetallic complexes, 3 can also be prepared by combining NaHMDS with heteroleptic [{Fe(DPA)(HMDS)}2] (2). In turn, 2 has been also synthesised and structurally defined by reacting [{Fe(HMDS)2}2] with two equivalents of DPA(H). Structural studies demonstrate the coordination flexibility of the N-bridged bis(heterocycle) ligand DPA, with 2 and 3 exhibiting discrete monomeric motifs, whereas 4 displays a much more intricate supramolecular structure, with one of its DPA ligands coordinating in an anti/anti fashion (as opposed to 2 and 3 where DPA shows a syn/syn conformation), which facilitates propagation of the structure via its central amido N. Magnetic studies confirmed the high-spin electron configuration of the iron(II) centres in all three compounds and revealed the existence of weak ferromagnetic interactions in dinuclear compound 2 (J = 1.01 cm -1 ). Journal Name ARTICLE

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Section: Introductionmentioning

confidence: 99%

Synthetic, structural and magnetic implications of introducing 2,2′-dipyridylamide to sodium-ferrate complexes

et al. 2017

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“…By combining soft organometallic compounds with alkali (or alkaline-earth metal) additives, bases have been more recently prepared and used to generate functionalized aromatic compounds including heterocycles. 6 Examples are R 2 Zn(TMP)LiÁ(TMEDA) (R = t Bu, Bu; TMP = 2,2,6,6-tetramethyl piperidino, TMEDA = N,N,N 0 ,N 0 -tetramethylethylenediamine) (described by the groups of Kondo, Uchiyama, Mulvey, and Hevia), 7 (TMP) 2 ZnÁ2MgCl 2 Á2LiCl 8 and TMPZnClÁLiCl 9 (Knochel), i Bu 3 Al (TMP)Li (Uchiyama and Mulvey), 10 Al(TMP) 3 Á3LiCl (Knochel), 11 (Me 3 SiCH 2 ) 2 Mn(TMP)LiÁTMEDA (Mulvey), 12 and MeCu(TMP)(CN) Li 2 (Uchiyama and Wheatley). 13 We recently accomplished the deproto-metalation of a large range of aromatics including heterocycles using a newly developed lithium-cadmium base, (TMP) 3 CdLi, in situ prepared from CdCl 2 ÁTMEDA and 3 equivalents of LiTMP.…”

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confidence: 99%

New Gilman-type lithium cuprate from a copper(II) salt: synthesis and deprotonative cupration of aromatics

Nguyen

Chevallier

Jouikov

et al. 2009

Tetrahedron Letters

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International audienceDeprotonative cupration of aromatics including heterocycles (anisole, 1,4-dimethoxybenzene, thiophene, furan, 2- fluoropyridine, 2-chloropyridine, 2-bromopyridine and 2,4-dimethoxypyrimidine) was realized in tetrahydrofuran at room temperature using the Gilman-type amido-cuprate (TMP)2CuLi in situ prepared from CuCl2*TMEDA through successive addition of 1 equivalent of butyllithium and 2 equivalents of LiTMP. The intermediate lithium (hetero)arylcuprates were evidenced by trapping with iodine, allyl bromide, methyl iodide and benzoyl chlorides, the latter giving the best results. Symmetrical dimers were also prepared from lithium azine and diazine cuprates using nitrobenzene as oxidative agent

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“…Through a coordination of the BF 3 group at the Nheterocyclic nitrogen the acidity of the pyridyl hydrogens increases, and the deprotonation of even electronrich pyridines such as 2-methoxypyridine (35) proceeds readily. Interestingly, the addition of BF 3 ·OEt may also dramatically change the direction of the deprotonation [42]. Thus, in the absence of this Lewis acid, the metalation of 35 with the aluminum base (tBu(R)N) 3 Al·3LiCl (36; R = tBu(iPr)CH) [42] proceeds in position 3 leading to the ketone 37 in 68 % yield after a copper-catalyzed acylation.…”

Section: The Directed Metalation Of Substituted Pyridinesmentioning

confidence: 99%

“…Interestingly, the addition of BF 3 ·OEt may also dramatically change the direction of the deprotonation [42]. Thus, in the absence of this Lewis acid, the metalation of 35 with the aluminum base (tBu(R)N) 3 Al·3LiCl (36; R = tBu(iPr)CH) [42] proceeds in position 3 leading to the ketone 37 in 68 % yield after a copper-catalyzed acylation. On the other hand, in the presence of BF 3 ·OEt 2 (1.1 equiv.…”

Section: The Directed Metalation Of Substituted Pyridinesmentioning

confidence: 99%

Review. Regioselective Functionalization of Pyridines using a Directed Metalation or a Halogen/Metal Exchange

Manolikakes

Barl

Sämann

et al. 2013

Zeitschrift Für Naturforschung B

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This review describes the various ways of functionalizing the pyridine scaffold using either directed metalation or halogen/metal exchange. Deprotonation can be accomplished with different lithium amides or alkyllithium reagents at low temperature. Milder conditions and higher functional group tolerance can be achieved by using ate-bases with different metals (Cd, Mg, Zn) or TMP (2,2,6,6-tetramethylpiperidyl) metal reagents (metal = Mg, Zn, Zr). With alkyllithium reagents it is also possible, by carefully adjusting the reaction conditions, to perform bromine/lithium exchange reactions. Organomagnesium reagents, like iPrMgX (X = Br, Cl·LiCl), may be used for exchanging more sensitive iodinated or brominated pyridines.

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Aluminum Bases for the Highly Chemoselective Preparation of Aryl and Heteroaryl Aluminum Compounds

Cited by 99 publications

References 62 publications

Synthetic, structural and magnetic implications of introducing 2,2′-dipyridylamide to sodium-ferrate complexes

Synthetic, structural and magnetic implications of introducing 2,2′-dipyridylamide to sodium-ferrate complexes

New Gilman-type lithium cuprate from a copper(II) salt: synthesis and deprotonative cupration of aromatics

Review. Regioselective Functionalization of Pyridines using a Directed Metalation or a Halogen/Metal Exchange

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