Suven Das

Superacid-catalysed arylation and rearrangement in 2 -hydroxy -2,2'-biindan-1,1'3,3'-tetrone and facile synthesis of 4-substituted phthalazinones

2-Hydroxy-2,2′-biindan-1,1′,3,3′-tetrone 1 upon stirring with moderately activated and deactivated arenes in superacidic triflic acid (CF3SO3H, TfOH) medium produces arylated adducts 2-aryl-2,2′-biindan-1,1′,3,3′-tetrones 3 within 1-2 h. Prolonged stirring (12–24 h) of the same reaction mixture gives rearranged products 3-(aryl-1,3-indanedionylmethylene)isobenzofuranones 4 involving three types of regioselectivity. The arylated adducts 3 and rearranged products 4 undergo nucleophilic ring opening and condensation with hydrazine hydrate to produce 4-substituted mono- and diphthalazinones depending upon the reaction temperature.

6-(α-Hydroxy-α-aryl/naphthyl)methyl-3,4-dihydro-2,5-benzodiazocin-1(2H)-ones and diphenylmethanes from C-2 arylated 1,3-indane-diones

Stirring 2-hydroxy-2-aryl-1,3-indanediones in ethylenediamine at room temperature for 1-2 h produces 6-(α-hydroxy-α-aryl/naphthyl)methyl-3,4-dihydro-2,5-benzodiazocin-1(2H)-ones in high yields. Under similar reaction conditions 2,2-diaryl-1,3-indanediones furnish diphenylmethanes.

Facile synthesis of 3-(diarylmethylene)isobenzofuranones, 4-(diarvlmethvl)-1(2H)-dhthalazinones and diarylmethanes

Reflux of 2,2-diaryl-1,3-indanediones in ethyleneglycol with a catalytic amount of triethylamine affords 3-(diarylmethylene)isobenzofuranones in very good yields. The latter produces 4-diarymethyl-1(2H)-phthalazinones under reflux in hydrazine hydrate (99%), and diarylmethanes upon stirring in ethylenediamine.

Acid catalysed condensation of 2-hydroxy-2,2'-biindan-1,1',3,3'-tetrone with enols

Various enolic compounds such as acetyl acetone, ethyl- and methyl-acetoacetate condense with 2-hydroxy-2, 2′-biindan-1,1′,3,3′-tetrone 1 in acid medium to produce adducts, which preferentially remain in the hemi-ketal form as confirmed by X-ray diffraction studies. 1 is also found to undergo acid catalysed dimerisation to furnish a cage like adduct fabricated by ketal and hemi-ketal linkages.