Novel cyclic tetraselenides of mannose: synthesis and mechanistic studies

In this Letter, we disclose the synthesis of novel cyclic tetraselenides starting from mannose which are very unusual and rare and have been synthesised for the first time. The structures are confirmed by X-ray analysis. The reactivity of the reagent tetraethylammonium tetraselenotungstate, (Et4N)2WSe4 has been compared with the well-known selenium transfer reagents Li2Se2 and Na2Se2. A tentative reaction mechanism has been proposed.