Bis(perchlorocatecholato)silane—A Neutral Silicon Lewis Super Acid

Maskey, Rezisha; Schädler, Marcel; Legler, Claudia; Greb, Lutz

doi:10.1002/anie.201712155

Cited by 116 publications

(90 citation statements)

References 61 publications

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“…The peak at -162 ppm has recently been reported as SiF 4 , [32] a species that has previously been reported to be formed as HF reacts with a glass surface. [33][34][35][36][37][38][39] The identity of SiF 4 in glass vessels was confirmed by headspace GC-MS (see SI for chromatogram and control experiments) of the reaction mixture.…”

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confidence: 99%

Vessel Effect in C–F Bond Activation Prompts Revised Mechanism and Reveals an Autocatalytic Glycosylation

et al. 2020

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Activation of C-F bonds under acidic conditions results in the formation of hydrogen fluoride as the reaction progresses. In the following communication, the effect of the vessel material on such reactions has been investigated and a significant difference between an HF-resistant material and common borosilicate glassware has been found. HF was found to react rapidly with borosilicate glassware, seemingly leaching fluoro- [a] 140 silicate into solution, but persisted in HF-resistant materials. Several examples of C-F bond activation on glycosyl fluorides and benzyl fluorides as well as NMR-studies suggest a significant effect of the choice of the reaction vessel, leading to the discovery of an autocatalytic glycosylation and a revised mechanism for the activation of benzyl fluorides, suggesting activation by SiF 4 rather than HF. Scheme 1. Examples of C-F bond activation promoted by acid-or H-bond catalysis and the work presented in this paper.

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confidence: 99%

Vessel Effect in C–F Bond Activation Prompts Revised Mechanism and Reveals an Autocatalytic Glycosylation

et al. 2020

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“…Hence, the large EA of the ligand and the positive charge on the B center in B[C 2 BNO(CN) 3 ] 3 and B[C 2 BNS(CN) 3 ] 3 confirm that these are stronger Lewis acids than B(C 6 F 5 ) 3 . To see if these can be classified as super Lewis acids, we have calculated their fluoride ion affinities (FIA) . A super Lewis acid is one whose FIA is larger than that of SbF 5 /SbF 6 − , namely >495–501 kJ mol −1 .…”

Section: Resultsmentioning

confidence: 99%

“…To see if these can be classified as super Lewis acids, we have calculated their fluoride ion affinities (FIA). [61][62][63][64][65] A super Lewis acid is one whose FIA is larger than that of SbF 5 /SbF 6 À , namely > 495-501 kJ mol À 1 . The FIA values of B[C 2 BNO(CN) 3 ] 3 and B[C 2 BNS(CN) 3 ] 3 , calculated at the wB97XD/6-31 + G(d, p) level, are 701 kJ mol À 1 and 630 kJ mol À 1 , respectively, making them super Lewis acids.…”

Section: Resultsmentioning

confidence: 99%

Superhalogens as Building Blocks of Super Lewis Acids

et al. 2019

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Lewis acids play an important role in synthetic chemistry. Using first‐principle calculations on some newly designed molecules containing boron and organic heterocyclic superhalogen ligands, we show that the acid strength depends on the charge of the central atom as well as on the ligands attached to it. In particular, the strength of the Lewis acid increases with increasing electron withdrawing power of the ligand. With this insight, we highlight the importance of superhalogen‐based ligands in the design of strong Lewis acids. Calculated fluoride ion affinity (FIA) values of B[C2BNO(CN)3]3 and B[C2BNS(CN)3]3 show that these are super Lewis acids.

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“…[ [7] Similarly,G reba nd co-workersh ave extended such reactivity to the neutral Si IV Lewis super acid, bis(perchlorocatecholato)silane. [8] Other approaches to CÀFa ctivation chemistry that exclude the use of transition metals are much less common. Mild bases such as K 2 CO 3 have been used in specialized cases.F or example, this base mediates CÀFa ctivation in a-fluorohydrazones or effects 1,2 or 1,5 fluorinem igrationsi nc yclopropyl-substituted fluoroepoxides.…”

Section: Introductionmentioning

confidence: 99%

C−F Bond Activation Mediated by Phosphorus Compounds

Bayne

Stephan

2019

Chemistry A European J

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The activation and functionalization of CÀFb onds has garnered significant attention in the scientificc ommunity as as trategy to mitigate toxicitya nd environmental concerns, as well as provide new pathways to agro-and pharmaceuticalc hemicals and materials. Although severalt ransition-metal-based systemsh ave been developed for this transformation,t he use of main-group compoundsr emains less explored. In recent years, several strategies for CÀF bond activation have focused on the use of phosphorusbased reagents. In this Minireview,a no verview of strategies is provided that exploits P V andP III -based Lewis acids as well as P III Lewis bases in frustrated Lewis pair (FLP) protocols for hydrodefluorination, CÀCc ouplings andC ÀFd erivatizations.

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Bis(perchlorocatecholato)silane—A Neutral Silicon Lewis Super Acid

Cited by 116 publications

References 61 publications

Vessel Effect in C–F Bond Activation Prompts Revised Mechanism and Reveals an Autocatalytic Glycosylation

Vessel Effect in C–F Bond Activation Prompts Revised Mechanism and Reveals an Autocatalytic Glycosylation

Superhalogens as Building Blocks of Super Lewis Acids

C−F Bond Activation Mediated by Phosphorus Compounds

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