TY - JOUR A1 - Krištofíková, Dominika A1 - Filo, Juraj A1 - Mečiarová, Mária A1 - Šebesta, Radovan T1 - Why do thioureas and squaramides slow down the Ireland–Claisen rearrangement? JF - Beilstein Journal of Organic Chemistry PY - 2019/// VL - 15 SP - 2948 EP - 2957 SN - 1860-5397 DO - 10.3762/bjoc.15.290 PB - Beilstein-Institut JA - Beilstein J. Org. Chem. UR - https://doi.org/10.3762/bjoc.15.290 KW - DFT calculations KW - green solvents KW - H-bonding catalysts KW - Ireland–Claisen rearrangement KW - silyl ketene acetals N2 - 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. ER -