Formation of Dimers of Some 2-Substituted Indan-1-one Derivatives during Base-Mediated Cross-Aldol Condensation

Unexpected dimers of some 2-substituted indan-1-one derivatives were isolated during aldol condensation of indan-1-one with various aldehydes in the presence of KOH (see Scheme). Monomeric products, usually expected from aldol condensation, further underwent a base-catalyzed nucleophilic addition reaction to their dimeric form in some cases. The structures of these dimers were characterized by using various spectral techniques and in one case, structural details were determined from a high-resolution crystallographic analysis.