Аннотация:Undesirable side processes responsible for fast deactivation of primary amino acid-derived organocatalysts in asymmetric aldol reactions have been identified. Novel ionic liquid-supported (S)-valine / (S)-a,a-diphenylserinol-derived catalyst 9 designed basing on these results exhibited much better recyclability in asymmetric syn-aldol reaction between hydroxyacetone and aldehydes. Furthermore, this catalyst appeared useful for the stereoselective synthesis of the naturally occurring 1(3H)-isobenzofuran-1-one scaffold via the asymmetric syn-aldol / lactonization cascade reaction.