Abstract
3-Acetylcoumarins (1) when treated with 2-mercaptobenzimidazole (2) in isopropanol containing iodine gave the title compound 3-[2-(1 H-benzimidazol-2-yl-sulfanyl)-acetyl]-chromen-2-ones (3). Alternatively, (3) could also be prepared by treating S-[2-oxo-2-(2-oxo-2H-chromen-2-yl)-ethyl] ester (5) with o-phenylenediamine (6). 5 itself was obtained from 1 by treatment with potassium salt of ethoxydithiocarbamate (4) in refluxing ethanol. The methylation of the title compound 3 was carried out-with DMS in acetonitrile containing K2CO3 and tetrabutylammonium bromide (TBAB) at RT to obtain 3-[2-(N-methylbenzimidazole-2-yl-sulfanyl)]-acetylchromen-2-ones (7). 7 could also be prepared by treating 5 with N-methyl-o-phenylenediamine (8). All the compounds were synthesized in good yields and their structures were established by spectral and analytical data.