Synthesis of 2‐Organylchalcogenyl–benzo[ b ]selenophenes: 1‐(2,2‐Dibromovinyl)‐2‐butylselenanylbenzenes as Precursors to Access Alkynes Susceptible to Cyclization

A convenient synthesis of 1‐(2‐organylchalcogenylethynyl)‐2‐butylselenanylbenzenes was established taking advantage of the selective reaction of 1‐(2,2‐dibromovinyl)‐2‐butylselenanylbenzenes with thiols or diorganyl diselenides. The new 1‐(2‐chalcogenylethynyl)‐2‐butylselenanylbenzenes were prepared in good yields and used as precursors of 2‐organylchalcogenylbenzo[ b ]selenophenes via electrophilic cyclization using I 2 , Br 2 or PhSeBr as electrophiles. Different classes of new 3‐substituted‐ (3‐iodo, 3‐bromo, 3‐phenylselenanyl) benzo[ b ]selenophenes were prepared in good yields. The synthetic application of the obtained products was demonstrated employing the benzo[ b ]selenophenes in Suzuki and Sonogashira cross‐coupling reactions.