Asian Journal of Chemistry Vol. 21, No. 6 (2009), 4251-4257 Facile and Eco-friendly Synthesis of 2-(2-Methoxyethyl sulfanyl)- 1H-benzimidazoles and Their Antimicrobial Screening DASARI VARAPRASAD, GANGULA MOHAN RAO, SUMANGALA RAO†, AKULA KALYAN CHAKRAVARTHY and BARU VIJAYAKUMAR* Department of Chemistry, C.K.M. College, Warangal-506 006, India E-mail: svpdasari@yahoo.co.in A simple and eco-friendly procedure for the preparation of 2-(2- methoxyethylsulfanyl)1H-benzimidazoles and their antimicrobial screening has been presented. Key Words: 2-Mercapto-5/6 substituted-1H-benzimidazoles, 2-(2-Methoxyethyl mesylate, Antimicrobial screening. INTRODUCTION Substituted benzimidazoles have been shown to exhibit a diversified biological activities. Many compounds containing this heterocyclic nucleus are of either industrial or biological importance. Similarly, 2-mercapto-1H-benzimidazole and its derivates have also been reported to have potent biological activities. Such as antihelmintics 1,2 and antibacterial and antiviral as well as anticancer activities. These structures mimics like purine bases in deoxy ribonucleic acids and ribonucleic acids. In our ongoing research programme, we are interested in synthesizing 2-(2- methoxyethylsulfanyl)benzimidazole nucleosides as probable anticancer agents 3 . EXPERIMENTAL Melting points are uncorrected and were recorded on a Perking-Elmer (AP1- 2000) Seris instrument. The progress of the reaction was followed by TLC (pre-coated silica gel plates-Merck) and visualization was done using iodine/UV lamp and charring in ninhydrin solution. IR spectra were recorded on Jasco FTIR (400-7000) instrument. 1 H and 13 C NMR spectra were recorded in CDCl 3 on a Varian-Gemini 200 MHz spectrometer using TMS as internal standard. General experimental procedure: The compounds (1a-h) 5 g was dissolved in 10 % NaOH solution (50 mL) and the alkylating agent, 2-methoxyethyl mesylate (1.1 eq) was added and the mass was stirred at room temperature for 12 h. The progress of the reaction was monitored by TLC. In case of nitro benzimidazole the reaction mass was heated up to 40-45 ºC, for 4 h. After completion of the reaction †Department of Microbiology, Padmavathi Degree College for Women, Warangal-506 006, India.