The First Solid-State Structure of a Lithiated Diazomethane with C–Li and N–Li Bonds: {[Me3SiC(Li)N2]2·3 THF}∞

Feeder, Neil; Hendy, Mark A.; Raithby, Paul R.; Snaith, Ronald; Wheatley, Andrew E. H.

doi:10.1002/(sici)1099-0690(199805)1998:5<861::aid-ejoc861>3.0.co;2-j

Cited by 14 publications

(5 citation statements)

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“…Initial DLPNO-CCSD(T) computations established a thermally feasible pathway from acetophenone ( 1 -Me,Ph) to 1-phenylpropyne ( 6 -Me,Ph), Figure . Consistent with Colvin and Hamill’s original proposal and later work by Gilbert, the diazoalkene MePhCCN 2 ( 4 -Me,Ph) was identified as a key intermediate, formed via a nucleophilic addition, , [1,3]-silyl migration, and elimination sequence. Although the ionic nature of the intermediates mean that quantitative comparisons made in the absence of explicit solvation should be interpreted with caution, lithiated silyl ether 3 -Me,Ph appears to be marginally favored over lithium alkoxide 2 -Me,Ph (Δ G 195K = −5 kJ mol –1 ), in a delicately balanced [1,3]-Brook equilibrium, − , in which pre-equilibrium between lithium α-diazoalkoxide 2 -Me,Ph and cyclic siliconate 7 -Me,Ph is kinetically insignificant.…”

Section: Resultssupporting

confidence: 66%

Systematic Evaluation of 1,2-Migratory Aptitude in Alkylidene Carbenes

et al. 2021

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Alkylidene carbenes undergo rapid inter-and intra-molecular reactions and rearrangements, including 1,2-migrations of β-substituents to generate alkynes. Their propensity for substituent migration exerts profound influence over the broader utility of alkylidene carbene intermediates, yet prior efforts to categorize 1,2-migratory aptitude in these elusive species have been hampered by disparate modes of carbene generation, ultrashort carbene lifetimes, mechanistic ambiguities, and the need to individually prepare a series of 13 C-labelled precursors. Herein we report on the rearrangement of 13 C-alkylidene carbenes generated in situ by the homologation of carbonyl compounds with [ 13 C]-Li-TMS-diazomethane, an approach that obviates the need for isotopically labelled substrates and has expedited a systematic investigation ( 13 C{ 1 H} NMR, DLPNO-CCSD(T)) of migratory aptitudes in an unprecedented range of more than 30 alkylidene carbenes. Hammett analyses of the reactions of 26 differentially substituted benzophenones reveal several counterintuitive features of 1,2-migration in alkylidene carbenes that may prove of utility in the study and synthetic application of unsaturated carbenes more generally.

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Section: Resultssupporting

confidence: 66%

Systematic Evaluation of 1,2-Migratory Aptitude in Alkylidene Carbenes

et al. 2021

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“…Finally, shorter than the Li−N(TMEDA) bonds previously noted for the bis ‐coordinating Lewis base molecules are those in which the TMEDA acts only as a monodentate donor [mean Li−N = 2.079 Å]. A comparison of the solid‐state structural parameters observed for 9 with those noted in 7 reveals that both C−N (mean 1.206 and 1.202 Å respectively for 9 and 7 ) and N−N (mean 1.214 and 1.208 Å) bond lengths correlate well but differ significantly from those in C ‐lithiated 1‐Li· 3 / 2 THF 19.…”

Section: Resultsmentioning

confidence: 95%

“…The reaction of 1‐H with n BuLi in THF yielded large yellow crystals of pure lithiated (trimethylsilyl)diazomethane 1 / 2 [{Me 3 SiC(Li)N 2 } 2 ·3THF] ( 1‐Li· 3 / 2 THF ), the solid‐state structure of which we have previously reported 19. X‐ray crystallography has shown 1‐Li· 3 / 2 THF to be a polymer based on a repeating tetramer unit (Figure 4), consisting of two ( mono ‐THF) complexed lithiodiazomethane molecules and two ( bis ‐THF) complexed ones i.e.…”

Section: Resultsmentioning

confidence: 99%

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Enantiospecific Synthesis of the (9S,18R)-Diastereomer of the Leukocyte Adhesion Inhibitor Cyclamenol A

Nazaré

Waldmann

2001

Chem. Eur. J.

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Cyclamenol A is one of the very few non-carbohydrate and non-peptide natural products that inhibit leukocyte adhesion to endothelial cells. We report on the first enantioselective total synthesis of the (9S, 18R)-diastereomer of this macrocyclic polyene lactam. Key elements of the synthesis are i) the synthesis of the required chiral building blocks by employing readily accessible building blocks from the chiral pool, that is, (S)-malic acid and (R)-hydroxyisobutyric acid, ii) assembly of a linear polyene precursor by means of Wittig and Horner olefination reactions as key C-C bond-forming transformations, iii) ring closure by means of a vanadium-mediated pinacolisation reaction and iv) conversion of the generated cis-diol into a (Z)-olefin to complete the entire polyene system of the natural product. Attempts to close the macrocyclic ring by a macrolactamisation, a double Stille coupling or direct olefination in a McMurry reaction failed. Crucial to the successful completion of the synthesis was the correct orchestration of the final steps. It was necessary to first deprotect the intermediate formed after macrocycle formation and to generate the sensitive heptaene system in the last step by means of a Corey-Hopkins sequence.

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“…However, a notable disparity in cation‐anion interaction is observed between LiFEA and LiETFSI. In LiFEA, a bond is formed between Li1‐N1 (2.069 Å), [9] contrasting with the broken Li1‐N1 ionic bond in LiETFSI. This distinction indicates that FEA anion exhibits a high DN [6] .…”

Section: Resultsmentioning

confidence: 99%

Rational Lithium Salt Molecule Tuning for Fast Charging/Discharging Lithium Metal Battery

Zhou,

Xia

et al. 2024

Angewandte Chemie

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The electrolytes for lithium metal batteries (LMBs) are plagued by a low Li+ transference number (T+) of conventional lithium salts and inability to form a stable solid electrolyte interphase (SEI). Here, we synthesized a self‐folded lithium salt, lithium 2‐[2‐(2‐methoxyethoxy)ethoxy]ethanesulfonyl(trifluoromethanesulfonyl) imide (LiETFSI), and comparatively studied with its structure analogue, lithium 1,1,1‐trifluoro‐N‐[2‐[2‐(2‐methoxyethoxy)ethoxy)]ethyl]methanesulfonamide (LiFEA). The special anion chemistry imparts the following new characteristics: i) In both LiFEA and LiETFSI, the ethylene oxide moiety efficiently captures Li+, resulting in a self‐folded structure and high T+ around 0.8. ii) For LiFEA, a Li‐N bond (2.069 Å) is revealed by single crystal X‐ray diffraction, indicating that the FEA anion possesses a high donor number (DN) and thus the intensive interphase “self‐cleaning” function for an ultra‐thin and compact SEI. iii) Starting from LiFEA, an electron‐withdrawing sulfone group is introduced near the N atom. The distance of Li‐N is tuned from 2.069 Å in LiFEA to 4.367 Å in LiETFSI. This alteration enhances ionic separation, achieves a more balanced DN, and tunes the self‐cleaning intensity for a reinforced SEI. Consequently, the fast charging/discharging capability of LMBs is progressively improved. This rationally tuned anion chemistry reshapes the interactions among Li+, anions, and solvents, presenting new prospects for advanced LMBs.

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The First Solid-State Structure of a Lithiated Diazomethane with C–Li and N–Li Bonds: {[Me3SiC(Li)N2]2·3 THF}∞

Abstract: Reaction of n‐butyllithium with Me3SiCHN2 in THF affords the first example of a lithiated diazomethane with C–Li and N–Li bonds.

Cited by 14 publications

References 20 publications

Systematic Evaluation of 1,2-Migratory Aptitude in Alkylidene Carbenes

Systematic Evaluation of 1,2-Migratory Aptitude in Alkylidene Carbenes

Enantiospecific Synthesis of the (9S,18R)-Diastereomer of the Leukocyte Adhesion Inhibitor Cyclamenol A

Rational Lithium Salt Molecule Tuning for Fast Charging/Discharging Lithium Metal Battery

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