FULL PAPER Facile Chemoselective synthesis of 2‐(2‐(Methoxycarbonyl)‐ 3‐oxo‐2,3‐dihydrobenzofuran‐2‐yl)benzoic acids and 3H,3’H‐ Spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives Neda Firoozi 1 | Zohreh Roshan 1 | Mohammad Reza Mohammadizadeh 1,2 1 Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Iran 2 Oil and Gas Research Center, Persian Gulf University, Bushehr 75169, Iran Correspondence Mohammad Reza Mohammadizadeh, Department of Chemistry, Faculty of Sciences, Persian Gulf University, Bushehr 75169, Iran. Email: mrmohamadizadeh@pgu.ac.ir Oxidation of some derivatives of 4b,9b–dihydroxyindeno[1,2‐b]benzofuran‐10‐ one have been investigated in detail using lead(IV) acetate in acetic acid under reflux conditions and periodic acid in aqueous ethanol at room temperature. We realized that during the first 5–15 minutes of the oxidation reactions in lead(IV) acetate/acetic acid system, 3H,3’H‐spiro[benzofuran‐2,1′‐isobenzofuran]‐ 3,3′‐dione derivatives have been synthesized chemo selectively, while, if the reaction mixtures stirred for additional 3 hours, the main products would be 2‐(2‐(Methoxycarbonyl)‐3‐oxo‐2,3‐dihydrobenzofuran‐2‐yl)benzoic acids. Moreover, room temperature oxidation of 4b,9b–dihydroxyindeno[1,2‐b] benzofuran‐10‐ones by periodic acid (H 5 IO 6 ), leads to the formation of 3H,3’H‐spiro[benzofuran‐2,1′‐isobenzofuran]‐3,3′‐dione derivatives in good to excellent yields. KEYWORDS 4b,9b–dihydroxyindenobenzofurans, benzofurans, lead(IV) acetate periodic acid, oxidation 1 | INTRODUCTION Benzofurans are naturally widespread molecules which have drawn considerable attention over the last few years due to their extensive physiological and pharma- cological properties. They display potent biological activites including antihyperglycemic, analgesic, antiparasitic, antimicrobial, antitumor, kinase inhibi- tor. [1–8] In addition, various natural and synthetic benzofuran derivatives, known as effective drugs, are used routinely in the treatment of different diseases (Figure 1). Amiodarone 1 is one of the most effective antiarrhythmic drugs with class III activity. Bufuralol 2 is a non‐specific β‐adrenergic blocker with affinity for both β 1 and β 2 ‐adrenergic receptors. It acts as a potent β‐adrenoceptor antagonist with partial agonist activity. Xanthotoxin 3 and Bergapten 4 are used as effective drugs for the treatment of skin conditions such as eczemain, vitiligo and severe psoriasis. Xanthotoxin 3 is also used to treat skin problems asso- ciated with a certain type of lymphoma. Usnic acid 5 is not only one of the most common and abundant lichen metabolites [9] , well known as an antibiotic, but also endowed with several other interesting prop- erties such as antigrowth, antiherbivore and anti‐ insect. [10] Besides medicinal and bilogical properties, substituted benzofurans find applications such as fluo- rescent sensor, oxidant, antioxidants, brightening agents and agriculture [11–13] As a result of these important properties, many research groups have investigated various methods for the synthesis and structural modification of benzofuran ring with the purpose of exploring their diverse biological activi- ties [14–19] Thus, benzofuran moiety can be taken as the lead compound for the synthesis of novel deriva- tives with a variety of chemical and biological activities. [20] Received: 5 January 2017 Revised: 21 May 2017 Accepted: 17 June 2017 DOI: 10.1002/aoc.3963 Appl Organometal Chem. 2017;e3963. https://doi.org/10.1002/aoc.3963 Copyright © 2017 John Wiley & Sons, Ltd. wileyonlinelibrary.com/journal/aoc 1 of 9