Synthesis and Spectral Characterization of Novel Spiroindan-1,3-Dione: A Diels Alder Adduct

DMSO/Ac2O reagent converts 1,3-indandione (1) to an unusual dimer 1H,1′H-2,2′-biindene-1,1′,3,3′(2H,2′H) tetrone and a dimeric condensation product along with an ylide (1a) at room temperature. This reagent also brings about oxidation of secondary alcohols to corresponding ketones, methyl thiomethylation, and N-hydroxymethylation in phthalimide and converts 4-hydroxycoumarins and dicoumarol to different oxidative and degradation products under varying conditions. However, when 1,3-indandione was refluxed with DMSO/Ac2O reagent at 150°C, it afforded a novel compound, 2-spiroindan 1,3-dione (2), a Diels Alder Adduct, analogous to (3) obtained upon treatment of 1,3-indandione with formaldehyde in presence of primary amines. 1. Introduction Dimethyl sulphoxide, a polar aprotic liquid, has been used in combination with a number of activators but the most important and extensively used was acetic anhydride. DMSO-acetic anhydride reagent has been a subject of monographs. It brings about oxidative rearrangements [1], oxidative degradation, oxidation of secondary alcohols [2], and methyl thiomethylates –OH group in different sugar units [3]. Interaction of this reagent with 4-hydroxy coumarins and 3-substituted 4-hydroxy coumarins results in a wide range of products under varying conditions both of mechanistic and pharmacological interests [4]. 1,3-Indandione, a member of class of I,3-diketo compounds has been found to yield a number of compounds with different substrates having marked chemical and biological activities. Its interaction with 5-bromo furfural in ethanol gives 5-bromo furfuryl diindandionyl-methane [5]. It reacts with cyclic ketones such as cyclopentanone and cyclohexanone to give the corresponding 2-cycloalkylidene-1,3-indandione [6]. 1,3-Indandione also reacts with indazoladione and furnishes a condensation product [7]. 3-Substituted-1,3-indandione shows Michael addition reaction with -nitro vinyl benzene to give an adduct having fungicidal property which depends upon the type and location of the substituent on aryl residue [8]. In a double Michael addition reaction 1,3-indandione has been found to interact with 1,5-diphenyl-pentadiene-3-one in a (？) quinone catalyzed stereo-specific reaction to give optically active trans-spiran [9]. 1,3-Indandione also undergoes condensation reaction with aromatic aldehydes to give 2-arylidine-1,3-indandione [10]. Reaction of 1,3-indandione with active methylene compounds such as malononitrile has been found to give a number of compounds [11]. Its condensation with heteroatom carbaldehydes has been found to