Short communication The efficient synthesis of aryl-5H-dibenzo[b,i]xanthene-5,7,12,14 (13H)-tetraone leuco-dye derivatives Zeinab Noroozi Tisseh, Seyyedeh Cobra Azimi, Peiman Mirzaei, Ayoob Bazgir * Department of Chemistry, Shahid Beheshti University, Tehran 1983963113, Iran article info Article history: Received 9 February 2008 Received in revised form 6 April 2008 Accepted 9 April 2008 Available online 18 April 2008 Keywords: Xanthenes Solvent-free 2-Hydroxynaphthalene-1,4-dione Aldehyde Dibenzo[b,i]xanthene Napthoquinone abstract An efficient method for the synthesis of 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14(13H)-tetraone derivatives by the reaction of 2-hydroxynaphthalene-1,4-dione and aldehydes in the presence of a catalytic amount of p-toluene sulfonic acid under solvent-free conditions at 100  C is described. Ó 2008 Published by Elsevier Ltd. 1. Introduction It is well known for many years that dyes have been most widely used in dyeing, as well as high technology as such as lasers, liquid crystalline displays, electro-optical devices and ink-jet printers [1,2]. Xanthene derivatives occupy an important position among different families of dyes, owing to a number of reasons related to their photochemical and photophysical properties [3]. Rose Bengal, Eosin, and other xanthene dyes are the most frequently employed dye-sensitizer when a quantitative interpretation of the photody- namic effect is required [4]. In recent years a number of analyte sensors have been designed using these scaffolds via synthesis of new xanthene based dyes [5]. Furthermore, xanthenes and benzoxanthenes have recently received great attention because of their wide range of therapeutic and biological properties, such as antibacterial [6], antiviral [7], and anti-inflammatory activities [8]. The other useful applications of these heterocycles are as leuco- dyes [9] and in laser technologies [10]. Molecules with the napthoquinone structure constitute one of the most interesting classes of compounds in organic chemistry, due to their biological properties, their industrial applications and their potential as intermediates in the synthesis of heterocycles [11]. A series of related napthoquinone pigments (streptocarpone, a-dunnione, dunniol and dunnione) from Streptocarpus dunnii have been isolated and characterized [12,13]. Considering the above reports, the development of new and simple synthetic methods for the efficient preparation of new xanthenes containing napthoquinone fragments is therefore an interesting challenge. In continuation of our previous works on synthesis of xanthene derivatives [14–16], herein, we report a simple and efficient method for the preparation of 13-aryl-5H-dibenzo[b,i] xanthene-5,7,12,14(13H)-tetraone derivatives under solvent-free conditions. To the best of our knowledge, this paper is the first report in the synthesis of some 13-aryl-5H-dibenzo[b,i]xanthene-5,7,12,14 (13H)-tetraones. 2. Experimental Melting points were measured on an Electrothermal 9100 apparatus and are uncorrected. Mass spectra were recorded on a FINNIGAN-MAT 8430 mass spectrometer operating at an ionization potential of 70 eV. 1 H NMR spectra were recorded on a BRUKER DRX-300 AVANCE spectrometer at 300.13 MHz. IR spectra were recorded on a Bomem MB-Series FT-IR spectropho- tometer. The chemicals used in this work were purchased from Fluka Chemical Company (Buchs, Switzerland). Elemental analyses were performed using a Heracus CHN-O-Rapid analyzer. 2.1. Typical procedure for the preparation of 13-aryl-5H-dibenzo [b,i]xanthene-5,7,12,14(13H)-tetraone 3 A mixture of 2-hydroxynaphthalene-1,4-dione (2 mmol), aldehyde (1 mmol) and p-toluene sulfonic acid (p-TSA) (0.1 g) * Corresponding author. Tel./fax: þ98 21 22431661. E-mail address: a_bazgir@sbu.ac.ir (A. Bazgir). Contents lists available at ScienceDirect Dyes and Pigments journal homepage: www.elsevier.com/locate/dyepig 0143-7208/$ – see front matter Ó 2008 Published by Elsevier Ltd. doi:10.1016/j.dyepig.2008.04.001 Dyes and Pigments 79 (2008) 273–275