Electronic effects in tautomeric equilibria: The case of chiral imines from D-glucamine and 2-hydroxyacetophenones
Electronic effects in tautomeric equilibria: The case of chiral imines from D-glucamine and 2-hydroxyacetophenones
A one-pot procedure for preparing a series of chiral imines by direct condensation of D-glucamine with 2-hydroxyacetophenones is described. Under conventional acetylation an unexpected mixture of two different peracetylated molecules is obtained, one with an open enamine structure, and the other incorporating an N-acetyl-1,3-oxazolidine into the acyclic skeleton. Surprisingly, both molecules coexist within the crystal's unit cell, as inferred from single-crystal X-ray analysis of a 5-bromo-substituted aryl derivative. Moreover, the 1,3-oxazolidine ring exists as rotational conformers (E,Z) owing to the restricted rotation around the N-acetyl bond. The equilibrium involving imine and enamine structures has been assessed in detail, providing in addition linear free-energy relationships between the tautomerization constants (KT) and the electronic effect of the substituents.
10209-10222
Matamoros, Esther
67ecaf15-3e62-46d8-b8fd-717f8e8c439a
Cintas, Pedro
29979233-8382-47a8-bde7-1faf4869308c
Light, Mark
cf57314e-6856-491b-a8d2-2dffc452e161
Palacios, Juan C.
2c06e379-89b3-46b1-95c8-7f5057732f9f
28 December 2019
Matamoros, Esther
67ecaf15-3e62-46d8-b8fd-717f8e8c439a
Cintas, Pedro
29979233-8382-47a8-bde7-1faf4869308c
Light, Mark
cf57314e-6856-491b-a8d2-2dffc452e161
Palacios, Juan C.
2c06e379-89b3-46b1-95c8-7f5057732f9f
Matamoros, Esther, Cintas, Pedro, Light, Mark and Palacios, Juan C.
(2019)
Electronic effects in tautomeric equilibria: The case of chiral imines from D-glucamine and 2-hydroxyacetophenones.
Organic & Biomolecular Chemistry, 17 (48), .
(doi:10.1039/C9OB02147G).
Abstract
A one-pot procedure for preparing a series of chiral imines by direct condensation of D-glucamine with 2-hydroxyacetophenones is described. Under conventional acetylation an unexpected mixture of two different peracetylated molecules is obtained, one with an open enamine structure, and the other incorporating an N-acetyl-1,3-oxazolidine into the acyclic skeleton. Surprisingly, both molecules coexist within the crystal's unit cell, as inferred from single-crystal X-ray analysis of a 5-bromo-substituted aryl derivative. Moreover, the 1,3-oxazolidine ring exists as rotational conformers (E,Z) owing to the restricted rotation around the N-acetyl bond. The equilibrium involving imine and enamine structures has been assessed in detail, providing in addition linear free-energy relationships between the tautomerization constants (KT) and the electronic effect of the substituents.
Text
Accepted-Ms-OB-ART-10-2019-002147
- Accepted Manuscript
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Accepted/In Press date: 15 November 2019
e-pub ahead of print date: 19 November 2019
Published date: 28 December 2019
Identifiers
Local EPrints ID: 436412
URI: http://eprints.soton.ac.uk/id/eprint/436412
ISSN: 1477-0520
PURE UUID: 238213d2-1f78-4016-97ca-388a578a4ae3
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Date deposited: 10 Dec 2019 17:30
Last modified: 17 Mar 2024 05:07
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Author:
Esther Matamoros
Author:
Pedro Cintas
Author:
Juan C. Palacios
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