Unusual enantioselectivities in heterogeneous organocatalyzed reactions: Reversal of direction using proline di- versus tri-peptides in the aldol addition

•Asymmetric aldol reactions were studied over supported di- and tri-peptides.•The ee reversed on tripeptide catalyst as compared to the dipeptide.•Quantum chemical calculations showed the conformation of the intermediates.•The stabilities of these intermediates were in agreement with the inversion found.