Cerium‐Catalyzed Hydrosilylation of Acrylates to Give α‐Silyl Esters

Pindwal, Aradhana; Patnaik, Smita; Everett, William C.; Ellern, Arkady; Windus, Theresa L.; Sadow, Aaron D.

doi:10.1002/anie.201610263

Cited by 25 publications

(32 citation statements)

References 34 publications

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“…These applications are highlighted by the synthesis of homoleptic silazido compounds and (bis-oxazolinato)lanthanide dialkyls and our recently reported catalytic hydrosilylation with 1b/B(C 6 F 5 ) 3 . 37 We are currently studying Ln{C(SiHMe 2 ) 3 } 3 as convenient precursors for single-site surface-supported catalysts and in polymerization chemistry.…”

Section: Discussionmentioning

confidence: 99%

Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds

et al. 2017

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Homoleptic tris(alkyl) rare earth complexes Ln{C(SiHMe)} (Ln = La, 1a; Ce, 1b; Pr, 1c; Nd, 1d) are synthesized in high yield from LnITHF and 3 equiv of KC(SiHMe). X-ray diffraction studies reveal 1a-d are isostructural, pseudo-C-symmetric molecules that contain two secondary Ln↼HSi interactions per alkyl ligand (six total). Spectroscopic assignments are supported by comparison with Ln{C(SiDMe)} and DFT calculations. The Ln↼HSi and terminal SiH exchange rapidly on the NMR time scale at room temperature, but the two motifs are resolved at low temperature. Variable-temperature NMR studies provide activation parameters for the exchange process in 1a (ΔH = 8.2(4) kcal·mol; ΔS = -1(2) cal·molK) and 1a-d (ΔH = 7.7(3) kcal·mol; ΔS = -4(2) cal·molK). Comparisons of lineshapes, rate constants (k/k), and slopes of ln(k/T) vs 1/T plots for 1a and 1a-d reveal that an inverse isotope effect dominates at low temperature. DFT calculations identify four low-energy intermediates containing five β-Si-H⇀Ln and one γ-C-H⇀Ln. The calculations also suggest the pathway for Ln↼HSi/SiH exchange involves rotation of a single C(SiHMe) ligand that is coordinated to the Ln center through the Ln-C bond and one secondary interaction. These robust organometallic compounds persist in solution and in the solid state up to 80 °C, providing potential for their use in a range of synthetic applications. For example, reactions of Ln{C(SiHMe)} and ancillary proligands, such as bis-1,1-(4,4-dimethyl-2-oxazolinyl)ethane (HMeC(Ox)) give {MeC(Ox)}Ln{C(SiHMe)}, and reactions with disilazanes provide solvent-free lanthanoid tris(disilazides).

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Section: Discussionmentioning

confidence: 99%

Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds

et al. 2017

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“…20 Lanthanide-catalyzed hydrosilylations of carbonyl compounds are uncommon, 21 although we recently reported a cerium-catalyzed hydrosilylation of acrylates that provides αsilyl esters. 22 In the present case, attempts to add more than one equivalent of acetophenone to 4 provided multiple, unidentified products. (6).…”

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confidence: 72%

Rare earth arylsilazido compounds with inequivalent secondary interactions

et al. 2018

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“…In the latter reaction, the Si−H bond activation is driven by a powerful nucleophilic ligand, and only occurred upon displacement of coordinating thf from the initial adduct [Ln{N(SiHMe 2 ) 2 } 3 (thf) 2 ]. In a recent study, a cerium(III) complex bearing a carbon‐based analogue to [N(SiHMe 2 ) 2 ], namely [Ce{C(SiHMe 2 ) 3 } 3 ], was shown to exhibit pronounced Ce⋅⋅⋅H−Si β‐agostic interactions at low temperatures in solution . Upon treatment of [Ce{C(SiHMe 2 ) 3 } 3 ] with B(C 6 F 5 ) 3 , β‐hydride abstraction occurred to afford borohydrido ligand [HB(C 6 F 5 ) 3 ] and disilacyclobutane as the co‐product, complementing previous similar findings …”

Section: Resultsmentioning

confidence: 99%

Emergence of a New [NNN] Pincer Ligand via Si−H Bond Activation and β‐Hydride Abstraction at Tetravalent Cerium

Werner

Bayer

Schädle

et al. 2020

Chemistry A European J

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The cerium(IV) pyrazolate complexes [Ce(Me2pz)4]2 and [Ce(Me2pz)4(thf)] initiate β‐hydride abstraction of the bis(dimethylsilyl)amido moiety, to afford a heteroleptic cerium(IV) species containing a dimethylpyrazolyl‐substituted silylamido ligand, namely [Ce(Me2pz)3(bpsa)] (bpsa=bis((3,5‐dimethylpyrazol‐1‐yl)dimethylsilyl)amido; Me2pz =3,5‐dimethylpyrazolato), along with some cerium(III) species. Remarkably, the nucleophilic attack of the pyrazolyl at the silicon atom and concomitant Si−H‐bond cleavage is restricted to the tetravalent cerium oxidation state and appears to proceed via the formation of a transient cerium(IV) hydride, which engages in immediate redox chemistry. When [Ce(Me2pz)4]2 is treated with [Li{N(SiMe3)2}], that is, in the absence of the SiH functionality, any redox chemistry did not occur. Instead, the ceric ate complex [LiCe2(Me2pz)9] and the stable mixed‐ligand ceric species [Ce(Me2pz)2{N(SiMe3)2}2] were obtained.

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Cerium‐Catalyzed Hydrosilylation of Acrylates to Give α‐Silyl Esters

Cited by 25 publications

References 34 publications

Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds

Homoleptic Trivalent Tris(alkyl) Rare Earth Compounds

Rare earth arylsilazido compounds with inequivalent secondary interactions

Emergence of a New [NNN] Pincer Ligand via Si−H Bond Activation and β‐Hydride Abstraction at Tetravalent Cerium

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