Simple and Efficient Synthesis of Isobenzofurans via Oxidation of Dihydroxyindenobenzofuran derivatives

Benzofurans have attracted a great deal of interest because of their presence ina large number of natural products, their biological activities, and their potential applications as pharmacological agents. For example, 5-benzofuranol has potent antiallergic and antiinflammatoryactivities [1]. Machicen diol, a benzofuran isolated from the extracts of Machilus glaucescens, a folk medicine, has been used in the treatment of asthma, rheumatism, and ulcers. In addition, benzofurans containing 1,3-thiazole derivatives have been reported to possess tuberculostatic, antibacterial, and antifungal activities [2]. As part of our continued interest for the development of newsynthetic methods for spiro-fused compounds [3], we report the oxidationof 4b,9b-dihydroxy-4b,9b-dihydro-10H-indeno[1,2-b]benzofuran-10- ones1 (Figure 1), as anew and simple route for the synthesis of novel 3H,3 Hspiro[ benzofuran-2,1 -isobenzofuran]-3,3 -dione derivatives 2.dihydroxy indeno benzo furanones1 were simply prepared using addition reaction of ninhydrin with substituted phenols and suffered the oxidative cleavage reaction with H5IO6 in aqueous media and at room temperature.The identification of the products 2 were occurred based on theirIR, Mass and NMR Spectra.