Microwave Induced Efficient Synthesis of 2-(1H-benzimidazol-2-ylthio)-4-methylquinoline

Quinoline derivatives posses wide class of biological activities [1,2,3,4,5]. Microwave heating has emerged as a powerful technique to promote a variety of chemical reaction is due to the short reaction time and the operational simplicity. So number of research paper has appeared proving the synthetic utility of MORE (Microwave-induced Organic Reaction Enhancement) chemistry in routine organic synthesis [6].

2-Chloro-4methylquinoline 1 (708 mg, 0.004 mol) and 2-mercaptobenzimidazole 2 (600 mg, 0.004 mol) were dissolved in minimum amount of anhydrous DMF. To this (552 mg, 0.004 mol) K₂CO₃ added, then the whole contents was irradiated under microwave oven for about 4 minutes at an interval of 1 min at 160 W. After the completion of reaction (monitored by TLC. ethyl acetate, pet ether 20:80), the reaction mixture was poured into ice-cold water. The obtained greenish yellow colour solid was filtered, washed with water then recrystallised from aqueous DMF, gaves 2-(1H-benzimidazol-2-ylthio)-4-methylquinoline 90 % yield.

Melting Point: 130-132 ^oC

MS (m/z, %): 292 ([M+H]⁺, 100%).

¹H NMR (400 MHz, DMSO-d6) ¦Ä (ppm): 2.45 (3H, s, Ar-CH₃), 7.22 (bs, 1H, NH), 6.90-7.92 (m, 9H, Ar−H), IR (KBr) ¦Í (cm⁻¹): 3150 (N-H), 1250 (C-S-C), 1650 (C=N).