Air- and Water-Tolerant Rare Earth Guanidinium BINOLate Complexes as Practical Precatalysts in Multifunctional Asymmetric Catalysis

Robinson, Jerome R.; Fan, Xinyuan; Yadav, J. S.; Carroll, Patrick J.; Wooten, Alfred J.; Pericàs, Miquel À.; Schelter, Eric J.; Walsh, Patrick J.

doi:10.1021/ja502568g

Cited by 46 publications

(34 citation statements)

References 113 publications

(44 reference statements)

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“…Chiral lanthanide complexes are interesting for their applications including enantioselective catalysis, detection of bio‐analytes, circularly polarized light emitting devices, and metal organic frameworks . The organic ligands define the Ln 3+ coordination sphere, modulating the access of further chemical species to the ion and making it soluble, stable, and persistent in various environments.…”

Section: Methodsmentioning

confidence: 99%

Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen‐Type Lanthanide (III) Complexes

et al. 2015

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The salen-type ligand prepared with (R,R) diphenylethan-1,2-diamine and salicylaldehyde provides stable and inert complexes KLnL2 upon simple reaction with lanthanide halides or pseudohalides LnX3 (Ln = Tb(3+) -Lu(3+) ; X = Cl(-) or TfO(-) ) of its potassium salt. All the complexes were completely characterized through nuclear magnetic resonance (NMR), electronic circular dichroism (ECD) in the UV and some (Er(3+) , Tm(3+) , Yb(3+) ) also with Near-IR ECD (NIR-ECD) and luminescence (Tb(3+) , Tm(3+) ). Careful analysis of the NMR shifts demonstrated that the complexes are isostructural in solution and afforded an accurate geometry. This was further confirmed by means of Density Functional Theory (DFT) optimization of the Lu(3+) complex, and by comparing the ligand-centered experimental and time-dependent TD-DFT computed UV-ECD spectra. As final validation, we used the NIR-ECD spectrum of the Yb(3+) derivative calculated by means of Richardson's equations. The excellent match between calculated and experimental ECD spectra confirm the quality of the NMR structure.

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Section: Methodsmentioning

confidence: 99%

Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen‐Type Lanthanide (III) Complexes

et al. 2015

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“…To overcome these challenges, we set out to develop precatalysts for the Shibasaki family of REMB catalysts. The idea was to replace the alkali metal cations with nitrogen-centered cations capable of H-bonding interactions . We found that the commercially available, inexpensive RE(NO 3 ) 3 ·(H 2 O) x salts could be used in the synthesis of RETMGHB up to a 25 g scale in combination with 3 equiv of ( S )-BINOL and 6 equiv of tetramethyl guanidine (TMG, Figure ).…”

Section: Understanding and Expansion Of The Catalysis Of Shibasaki’s ...mentioning

confidence: 99%

Expanding the Rare-Earth Metal BINOLate Catalytic Multitool beyond Enantioselective Organic Synthesis

et al. 2021

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Metrics & MoreArticle Recommendations CONSPECTUS: Shibasaki's rare earth alkali metal BINOLate (REMB) framework has provided chemists with a general catalyst platform to access a range of enantioenriched small molecules from the single, commercially available pro-ligand (R)-or (S)-BINOL. A defining feature of these heterobimetallic frameworks is the high level of catalyst tunability, achieved through the simple modulation of the central rare-earth cation and peripheral alkali metal cations. While this family of multifunctional catalysts displays impressive generality and catalytic capability, detailed mechanistic understanding of these complex, multimetallic systems was lacking prior to our investigations. This backdrop served as initial inspiration for our investigations of this privileged class of complexes over the past decade, which have led to new and exciting advances in catalysis and beyond.In this Account, we describe our investigations using Shibasaki's framework focusing on the central metal-ion, the BINOLate ligands, and the secondary sphere cations. Our studies began with an investigation into the Lewis acidity of the complexes, where we demonstrated that Lewis bases readily coordinate to REMB frameworks when lithium occupies the secondary coordination sphere. This observation was contrasted by the complexes containing sodium or potassium in the secondary coordination sphere, as the rare earth cation is evidently less accessible for substrate binding. Our efforts in understanding the ligand exchange of the complexes enabled the discovery that associative processes dominate the mechanism of ligand exchange and LA/LA (Lewis acid/Lewis acid) and LA/BB (Lewis acid/Brønsted base) catalysis by the REMB frameworks.Replacing metal cations in the secondary coordination sphere with the N,N,N′,N′-tetramethylguanidinium cation delivered an effective precatalyst that is air and water stable over the course of 6 months.To expand the reactivity of the REMB, we investigated the ability of U IV cations to occupy the primary coordination sphere and ZnEt + and Cu(DBU) + cations to occupy the secondary coordination sphere. Synthesizing the REMB complexes using the thiol congener monothioBINOL provided an unusual anionic REMB framework, driven by the oxophilicity of the lithium cations. Using the REMB as a platform for investigating the Ce III /Ce IV redox couple, we demonstrated that, while oxidative cerium functionalization is observed in the case of lithium containing REMBs, salt elimination is observed in the sodium, potassium, and cesium containing REMBs. Furthermore, we found that while the rate of heterogeneous electron transfer for Ce III was k s (Cs I ) > k s (K I ) > k s (Na I ) > k s (Li I ), the rates of reaction with the oxidant trityl chloride trended in the opposite order with k obs (Li I ) ≫ k obs (Na I ) > k obs (K I ) > k obs (Cs I ). We attribute this to the ability to form inner-sphere complexes with the oxidant, rather than differences in redox potential or reorganization energies. Applying our knowle...

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“…The real catalyst C10 can be formed in situ, and one acyclic ketoester 1d was tested, and the corresponding Michael addition product was produced in good yield with excellent 99% ee (Scheme 14). 18 In 2015, Sugimura and co-workers developed an asymmetric 1,4-addition reaction of 2-formyl(thio)esters to vinylketones using a newly developed thiourea-tertiary amine catalyst C11 involving a quaternary carbon stereocenter construction in an acyclic system. In all cases, excellent enantioselectivities were observed for the products (Scheme 15).…”

Section: Michael Additions Mediated By Acyclic α-Substituted-β-ketocarbonylsmentioning

confidence: 99%

Asymmetric catalytic construction of fully substituted carbon stereocenters using acyclic α-branched β-ketocarbonyls: the “Methyl Rule” widely exists

2020

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Air- and Water-Tolerant Rare Earth Guanidinium BINOLate Complexes as Practical Precatalysts in Multifunctional Asymmetric Catalysis

Cited by 46 publications

References 113 publications

Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen‐Type Lanthanide (III) Complexes

Synthesis, Structural Characterization, and Chiroptical Studies of Bidentate Salen‐Type Lanthanide (III) Complexes

Expanding the Rare-Earth Metal BINOLate Catalytic Multitool beyond Enantioselective Organic Synthesis

Asymmetric catalytic construction of fully substituted carbon stereocenters using acyclic α-branched β-ketocarbonyls: the “Methyl Rule” widely exists

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