Modulation of imine chemistry with intramolecular hydrogen bonding: Effects from ortho-OH to NH
Salicylaldehyde derivatives and their imines are important building blocks in organic and supramolecular chemistry. In an effort to expand structural diversity in the current work we changed ortho-OH in salicylaldehyde to NH of amide/sulfonamide and investigated the effect of resulting intramolecula...
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Veröffentlicht in: | Tetrahedron 2020-04, Vol.76 (17), p.131128, Article 131128 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Salicylaldehyde derivatives and their imines are important building blocks in organic and supramolecular chemistry. In an effort to expand structural diversity in the current work we changed ortho-OH in salicylaldehyde to NH of amide/sulfonamide and investigated the effect of resulting intramolecular hydrogen bonds on imine dynamic covalent chemistry (DCC). A suite of ortho-aminobenzaldehydes were readily synthesized, and X-ray and NMR data validated the existence of NH⋯O intramolecular hydrogen bonds. The formation and exchange of imines were then studied in acetonitrile, and the acidity of OH/NH significantly influenced the thermodynamics and kinetics of imine reactions. Furthermore, the role of OH/NH⋯N hydrogen bonds on imines was elucidated by the shift of aldehyde exchange equilibrium. Finally, the formation of imines was achieved in aqueous solutions. The mechanistic insights could pave the way for future applications in assembly and labelling.
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•The replacement of OH in salicylaldehyde with NH of amide/sulfonamide.•The impact of intramolecular hydrogen bonding on imine formation and exchange.•Mechanistic insights for future design. |
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ISSN: | 0040-4020 1464-5416 |
DOI: | 10.1016/j.tet.2020.131128 |