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Updated: Dec 31, 2025

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Why do thioureas and squaramides slow down the Ireland-Claisen rearrangement?
Dominika Krištofíková1, Juraj Filo2, Mária Mečiarová1
1Department of Organic Chemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Mlynská dolina, Ilkovičova 6, 84215 Bratislava, Slovakia.
Abstract:
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.
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