Synthesis of 3‐Organoselenyl Quinolines through the Reduction of Alkynes Mediated by Electrophilic Organoselenium Compounds

Abstract A methodology for the synthesis and functionalization of quinolines was developed. This approach involves the cyclization of 2‐amino arylalkynyl ketones to 3‐(organoselanyl)‐4‐iodoquinolines through a sequential reaction pathway. The process includes: (i) in situ formation of an electrophilic organoselenyl species, (ii) activation of the alkyne‘s carbon‐carbon bond via a seleniranium ion intermediate, (iii) anti‐nucleophilic attack of iodide on the activated triple bond, and (iv) subsequent condensation. The resulting 3‐(organoselanyl)‐4‐iodoquinolines were demonstrated to be versatile substrates, efficiently undergoing Sonogashira cross‐coupling to produce 4‐alkynyl‐quinolines and Ullmann‐type reactions to yield the corresponding sulfides. Furthermore, the 4‐alkynyl‐quinolines were readily converted into selenophene derivatives via halogen‐promoted electrophilic cyclization, highlighting the broad applicability of the developed method.