Revisiting the Mg/TMSCl/Dipolar Solvent System for Dearomatic Silylation of Aryl Carbonyl Compounds: Substrate Scope, Transformations, and Mechanistic Studies

Li, Nannan; Li, Meng; Gao, Jiani; Zhong, Zhou; Xie, Jian‐Bo

doi:10.1021/acs.joc.2c01178

Cited by 2 publications

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References 60 publications

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“…The reaction is further complicated by the trimethylsilyl substitution byproduct. Alkylation of bipyridine is known through its reaction with alkyllithium reagents [59] and silylation of bipyridyl carbons is possible through a variety of means [60–62] . However, the silylation of bipyridine by its reaction with trimethylsilylazide is highly unusual and highlights the difficulty of predicting the outcome of these reactions, even when the stoichiometry is carefully controlled.…”

Section: Resultsmentioning

confidence: 99%

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C₅Me₅ and Polyazide Complexes

Stennett,

Ziller,

Evans

2024

Eur J Inorg Chem

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Exploration of the reduction chemistry of the 2,2’‐bipyridine (bipy) lanthanide metallocene complexes Cp*2LnCl(bipy) and Cp*2Ln(bipy) (Cp* = C5Me5) resulted in the isolation of a series of complexes with unusual composition and structure including complexes with a single Cp* ligand, multiple azide ligands, and bipy ligands with close parallel orientations. These results not only reveal new structural types, but they also show the diverse chemistry displayed by this redox‐active platform. Treatment of Cp*2NdCl(bipy) with excess KC8 resulted in the formation of the mono‐Cp* Nd(III) complex, [K(crypt)]2[Cp*Nd(bipy)2], 1, as well as [K(crypt)][Cp*2NdCl2], 2, and the previously reported [K(crypt)][Cp*2Nd(bipy)]. A mono‐Cp* Lu(III) complex, Cp*Lu(bipy)2, 3, was also found in an attempt to make Cp*2Lu(bipy) from LuCl3, 2 equiv. of KCp*, bipy, and K/KI. Surprisingly, the (bipy)1− ligands in neighboring molecules in the structure of 3 are oriented in a parallel fashion with intermolecular C⋅⋅⋅C distances of 3.289(4) Å, which are shorter than the sum of van der Waals radii of two carbon atoms, 3.4 Å. Another product with one Cp* ligand per lanthanide was isolated from the reaction of [K(crypt)][Cp*2Eu(bipy)] with azobenzene, which afforded the dimeric Eu(II) complex, [K(crypt)]2[Cp*Eu(THF)(PhNNPh)]2, 4. Attempts to make 4 from the reaction between Cp*2Eu(THF)2 and a reduced azobenzene anion generated instead the mixed‐valent Eu(III)/Eu(II) complex, [K(crypt)][Cp*Eu(THF)(PhNNPh)]2, 5, which allows direct comparison with the bimetallic Eu(II) complex 4. Mono‐Cp* complexes of Yb(III) are obtained from reactions of the Yb(II) complex, [K(crypt)][Cp*2Yb(bipy)], with trimethylsilylazide, which afforded the tetra‐azido [K(crypt)]2[Cp*Yb(N3)4], 6, or the di‐azido complex [K(crypt)]2[Cp*Yb(N3)2(bipy)], 7 a, depending on the reaction stoichiometry. A mono‐Cp* Yb(III) complex is also isolated from reaction of [K(crypt)][Cp*2Yb(bipy)] with elemental sulfur which forms the mixed polysulfido Yb(III) complex [K(crypt)]2[Cp*Yb(S4)(S5)], 8 a. In contrast to these reactions that form mono‐Cp* products, reduction of Cp*2Yb(bipy) with 1 equiv. of KC8 in the presence of 18‐crown‐6 resulted in the complete loss of Cp* ligands and the formation of [K(18‐c‐6)(THF)][Yb(bipy)4], 9. The (bipy)1− ligands of 9 are arranged in a parallel orientation, as observed in the structure of 3, except in this case this interaction is intramolecular and involves pairs of ligands bound to the same Yb atom. Attempts to reduce further the Sm(II) (bipy)1− complex, Cp*2Sm(bipy) with 2 equiv. of KC8 in the presence of excess 18‐crown‐6 led to the isolation of a Sm(III) salt of (bipy)2− with an inverse sandwich Cp* counter‐cation and a co‐crystallized K(18‐c‐6)Cp* unit, [K2(18‐c‐6)2Cp*]2[Cp*2Sm(bipy)]2 ⋅ [K(18‐c‐6)Cp*], 10.

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Section: Resultsmentioning

confidence: 99%

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C₅Me₅ and Polyazide Complexes

Stennett,

Ziller,

Evans

2024

Eur J Inorg Chem

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Partial Reduction of Benzenoid Aromatic Rings by Dissolving Metals and by Other Methods

Clemente,

Coelho

2024

Reference Module in Chemistry, Molecular Sciences and Chemical Engineering

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Revisiting the Mg/TMSCl/Dipolar Solvent System for Dearomatic Silylation of Aryl Carbonyl Compounds: Substrate Scope, Transformations, and Mechanistic Studies

Cited by 2 publications

References 60 publications

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C₅Me₅ and Polyazide Complexes

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C₅Me₅ and Polyazide Complexes

Partial Reduction of Benzenoid Aromatic Rings by Dissolving Metals and by Other Methods

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Revisiting the Mg/TMSCl/Dipolar Solvent System for Dearomatic Silylation of Aryl Carbonyl Compounds: Substrate Scope, Transformations, and Mechanistic Studies

Cited by 2 publications

References 60 publications

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C5Me5 and Polyazide Complexes

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C5Me5 and Polyazide Complexes

Partial Reduction of Benzenoid Aromatic Rings by Dissolving Metals and by Other Methods

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Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C₅Me₅ and Polyazide Complexes

Reduced 2,2’‐Bipyridine Lanthanide Metallocenes Provide Access to Mono‐C₅Me₅ and Polyazide Complexes