Metal-Free Borylation of Heteroarenes Using Ambiphilic Aminoboranes: On the Importance of Sterics in Frustrated Lewis Pair C-H Bond Activation
| Autor: | Luis C. Misal Castro, Julien Légaré Lavergne, Arumugam Jayaraman, Frédéric-Georges Fontaine, Étienne Rochette |
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| Rok vydání: | 2017 |
| Předmět: |
Steric effects
C h bond 010405 organic chemistry Stereochemistry Chemistry General Chemistry 010402 general chemistry 01 natural sciences Biochemistry Medicinal chemistry Borylation Catalysis Frustrated Lewis pair Dissociation (chemistry) 0104 chemical sciences Colloid and Surface Chemistry Metal free Density functional theory |
| Zdroj: | Journal of the American Chemical Society. 139(41) |
| ISSN: | 1520-5126 |
| Popis: | Two novel frustrated Lewis pair (FLP) aminoboranes, (1-Pip-2-BH2-C6H4)2 (2; Pip = piperidyl) and (1-NEt2-2-BH2-C6H4)2 (3; NEt2 = diethylamino), were synthesized, and their structural features were elucidated both in solution and in the solid state. The reactivity of these species for the borylation of heteroarenes was investigated and compared to previously reported (1-TMP-2-BH2-C6H4)2 (1; TMP = tetramethylpiperidyl) and (1-NMe2-2-BH2-C6H4)2 (4; NMe2 = dimethylamino). It was shown that 2 and 3 are more active catalysts for the borylation of heteroarenes than the bulkier analogue 1. Kinetic studies and density functional theory calculations were performed with 1 and 2 to ascertain the influence of the amino group of this FLP-catalyzed transformation. The C–H activation step was found to be more facile with smaller amines at the expense of a more difficult dissociation of the dimeric species. The bench-stable fluoroborate salts of all catalysts (1F–4F) have been synthesized and tested for the borylation rea... |
| Databáze: | OpenAIRE |
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