Structural constraints for C2-symmetric heterocyclic organocatalysts in asymmetric aldol reactionsLaars, Marju; Kriis, Kadri; Kailas, Tiiu; Müürisepp, Aleksander-Mati; Pehk, Tõnis; Kanger, Tõnis; Lopp, MargusTetrahedron : asymmetry2008 / p. 641-645 https://www.researchgate.net/publication/244242681_Structural_constraints_for_C_2-symmetric_heterocyclic_organocatalysts_in_asymmetric_aldol_reactions