Why do thioureas and squaramides slow down the Ireland-Claisen rearrangement?

DFT calculations H-bonding catalysts Ireland–Claisen rearrangement green solvents silyl ketene acetals

Journal

Beilstein journal of organic chemistry
ISSN: 1860-5397
Titre abrégé: Beilstein J Org Chem
Pays: Germany
ID NLM: 101250746

Informations de publication

Date de publication:
2019
Historique:
received: 28 05 2019
accepted: 25 11 2019
entrez: 11 1 2020
pubmed: 11 1 2020
medline: 11 1 2020
Statut: epublish

Résumé

A range of chiral hydrogen-bond-donating organocatalysts was tested in the Ireland-Claisen rearrangement of silyl ketene acetals. None of these organocatalysts was able to impart any enantioselectivity on the rearrangements. Furthermore, these organocatalysts slowed down the Ireland-Claisen rearrangement in comparison to an uncatalyzed reaction. The catalyst-free reaction proceeded well in green solvents or without any solvent. DFT calculations showed that the activation barriers are higher for reactions involving hydrogen-donating organocatalysts and kinetic experiments suggest that the catalysts bind stronger to the starting silyl ketene acetals than to transition structures thus leading to inefficient rearrangement reactions.

Identifiants

pubmed: 31921366
doi: 10.3762/bjoc.15.290
pmc: PMC6941421
doi:

Types de publication

Journal Article

Langues

eng

Pagination

2948-2957

Informations de copyright

Copyright © 2019, Krištofíková et al.; licensee Beilstein-Institut.

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Auteurs

Dominika Krištofíková (D)

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 84215 Bratislava, Slovakia.

Juraj Filo (J)

Institute of Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 84215 Bratislava, Slovakia.

Mária Mečiarová (M)

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 84215 Bratislava, Slovakia.

Radovan Šebesta (R)

Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 84215 Bratislava, Slovakia.

Classifications MeSH