Abstract
A number of hitherto unreported 2H‐benzothiopyrano[3,2‐c]quinolin‐7(8H)‐ones have been regioselectively synthesized in 90–96% yield by tri‐n‐butyltinhydride–AIBN–mediated radical cyclization from 4‐(2′‐bromothioarylmethyl)‐1‐methylquinolin‐2(1H)‐ones and their corresponding sulfones. 4‐(2′‐Bromothioarylmethyl)quinolin‐2(1H)‐ones were in turn prepared from 4‐bromomethylquinolin‐2(1H)‐one and o‐bromothiophenols by refluxing in acetone in the presence of anhydrous K2CO3. These were converted to the corresponding sulfones by oxidation with two equivalents of m‐CPBA in refluxing dichloromethane for 1 h.
Acknowledgments
N. Kundu is thankful to Council of Scientific and Industrial Research (CSIR) (New Delhi) for a senior research fellowship. We also thank Department of Science and Technology (DST) (New Delhi) for providing a UV‐Vis spectrophotometer and FT‐IR spectrometer under the Department of Science and Technology‐Financial assistance for Infrastructural Development of Science and Technology (DST‐FIST) program.