Accurate measurement of effective Li–Li scalar coupling constants: the NMR missing link for alkyllithium aggregates

Hédouin, Matthieu; Harrison‐Marchand, Anne; Maddaluno, Jacques; Oulyadi, Hassan

doi:10.1039/d0cc06871c

Cited by 3 publications

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“…Noteworthy for this study are several reported NMR investigations on a series of naphthyllithium compounds [19] and several ortho-dimethylaminoÀ aryllithium compounds [20] in solution. Additionally, there are approaches to utilise 7 Li residual quadrupolar couplings to identify the degree of organolithium aggregation in gels, [21] DOSY, [22] classic 7 Li, [23] and scalar LiÀ Li couplings [24] in NMR spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Amino−Organolithium Compounds and their Aggregation for the Synthesis of Amino−Organoaluminium Compounds

et al. 2021

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Here, we present a thorough structural study of small, easily accessible aminoÀ organolithium compounds with bridging phenyl and naphthyl moieties. Their crystal structures most likely represent their aggregation as tetramers and dimers in both hydrocarbon and ethereal solvents. These aminoÀ organolithium compounds were further used to generate their corresponding aluminium compounds as a model system. Their crystal structures are reported too. All structures are discussed with a focus on the different steric demands and bridging moieties. Additionally, the crystal structures of neophyllithium and decomposition products of some of the compounds mentioned above are reported. This study provides additional data for the future design and synthesis of amine stabilised organolithium and -aluminium compounds.

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Section: Introductionmentioning

confidence: 99%

Amino−Organolithium Compounds and their Aggregation for the Synthesis of Amino−Organoaluminium Compounds

et al. 2021

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NMR and DFT Studies with a Doubly Labelled¹⁵N/⁶LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

et al. 2022

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This work shows why it is imperious to use an excess of butyllithium for a directed ortho‐lithiation of a trifluoromethyl sulfoximine. The analysis of mixtures of n‐BuLi and sulfoximine 1 in THF‐d8 using {1H, 6Li, 13C, 15N, 19F} NMR experiments at low temperatures reveal that a first deprotonation occurs that leads to dimeric and tetrameric N‐lithiated sulfoximine (93 : 7). Using an excess n‐BuLi (5 equivalents), the second deprotonation on the ortho‐position of the aromatic occurs. Six species were observed and characterized on the way. It includes three aggregates involving a sulfoximine: i) a [dilithiated sulfoximine/(n‐BuLi)] dimer solvated by four molecules of THF (Agg2, 39 %); ii) a [dilithiated sulfoximine/(n‐BuLi)3] tetramer solvated by six molecules of THF (Agg3, 39 %); iii) a [dilithiated sulfoximine/(n‐BuOLi)3] tetramer solvated by four molecules of THF (Agg1, 22 %). A DFT study afforded optimized solvated structures for all these aggregates, fully consistent with the NMR data.

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NMR and DFT Studies with a Doubly Labelled¹⁵N/⁶LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

et al. 2022

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This work shows why it is imperious to use an excess of butyllithium for a directed ortho-lithiation of a trifluoromethyl sulfoximine. The analysis of mixtures of n-BuLi and sulfoximine 1 in THF-d 8 using { 1 H, 6 Li, 13 C, 15 N, 19 F} NMR experiments at low temperatures reveal that a first deprotonation occurs that leads to dimeric and tetrameric N-lithiated sulfoximine (93 : 7). Using an excess n-BuLi (5 equivalents), the second deprotonation on the ortho-position of the aromatic occurs. Six species were observed and characterized on the way. It includes three aggregates involving a sulfoximine: i) a [dilithiated sulfoximine/(n-BuLi)] dimer solvated by four molecules of THF (Agg2, 39 %); ii) a [dilithiated sulfoximine/(n-BuLi) 3 ] tetramer solvated by six molecules of THF (Agg3, 39 %); iii) a [dilithiated sulfoximine/(n-BuOLi) 3 ] tetramer solvated by four molecules of THF (Agg1, 22 %). A DFT study afforded optimized solvated structures for all these aggregates, fully consistent with the NMR data.

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Accurate measurement of effective Li–Li scalar coupling constants: the NMR missing link for alkyllithium aggregates

Abstract: Alkyllitium mixed aggregates: dynamics-free value of the 2JLi–Li as a simple access to various structural factors, including the dynamics, solvation and the steric hindrance of alkyl chains.

Cited by 3 publications

References 38 publications

Amino−Organolithium Compounds and their Aggregation for the Synthesis of Amino−Organoaluminium Compounds

Amino−Organolithium Compounds and their Aggregation for the Synthesis of Amino−Organoaluminium Compounds

NMR and DFT Studies with a Doubly Labelled¹⁵N/⁶LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

NMR and DFT Studies with a Doubly Labelled¹⁵N/⁶LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

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Accurate measurement of effective Li–Li scalar coupling constants: the NMR missing link for alkyllithium aggregates

Abstract: Alkyllitium mixed aggregates: dynamics-free value of the 2JLi–Li as a simple access to various structural factors, including the dynamics, solvation and the steric hindrance of alkyl chains.

Cited by 3 publications

References 38 publications

Amino−Organolithium Compounds and their Aggregation for the Synthesis of Amino−Organoaluminium Compounds

Amino−Organolithium Compounds and their Aggregation for the Synthesis of Amino−Organoaluminium Compounds

NMR and DFT Studies with a Doubly Labelled15N/6LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

NMR and DFT Studies with a Doubly Labelled15N/6LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

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NMR and DFT Studies with a Doubly Labelled¹⁵N/⁶LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi

NMR and DFT Studies with a Doubly Labelled¹⁵N/⁶LiS‐Trifluoromethyl Sulfoximine Reveal Why a Directedortho‐Lithiation Requires an Excess ofn‐BuLi