Bromoallenes as Allyl Dication Equivalents in the Presence or Absence of Palladium(0): Direct Construction of Bicyclic Sulfamides Containing Five- to Eight-membered Rings by Tandem Cyclization of Bromoallenes
catalyst to afford cyclosulfamides containing five- or six-membered rings. While the palladium-free cyclization is dependent on the substrate structure affording the bicyclic sulfamides through the first cyclization onto the proximal or central carbon atom of the bromoallenes, the palladium-catalyzedreaction strongly promotes the first cyclization onto the central allenic carbon atom to afford bicyclic
Novel and efficient synthesis of medium-sized heterocycles such as azepine, oxepine, and benzo[d]azocine derivatives is described. Treatment of bromoallenes having a nucleophilic moiety with sodiumalkoxide and a palladium(0) catalyst in the presence of an alcohol leads to regioselective formation of medium-sized rings at the central position of the allenic carbon.