Synthesis and characterization of novel indanone-based spiro-dihydrobenzofuran derivatives

In this study, the synthesis and characterization of novel indanone-based spiro-dihydrobenzofuran derivatives were examined. Firstly, chalcone-like compounds 4a-k, (E)-2-benzylidene-2,3-dihydro-1H-inden-1-one derivatives, were synthesized by the base-catalyzed addition of benzaldehyde derivatives to 2,3-dihydro-1 H-inden-1-one. Then Mn(OAc)(3)-mediated addition of dimedone (2) to the chalcone-like compounds gave two novel spiro-dihydrobenzofuran isomers: (3 S) -6,6-dimethyl-3-aryl-6,7-dihydro-3 H-spiro [benzofuran-2,2'-indene]-1',4(3' H ,5 H) -dione (5a-k) and (2' S)-6 ,6-dimethyl-2-aryl-6 ,7-dihydro-2 H-spiro [benzofuran-3,2'-indene]-1' ,4 (3' H ,5 H) -dione (6a-k) in good yields. The isomers were separated by column chromatography and their structures were elucidated on the basis of spectral data (NMR, IR) and elemental analysis.