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

✍ Scribed by Hisao Hamaguchi; Shohei Kosaka; Hiroaki Ohno; Nobutaka Fujii; Tetsuaki Tanaka

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 365 KB
• Volume: 13
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/chem.200601373

✦ Synopsis

Abstract

A highly regioselective synthesis of bicyclic sulfamides is described. Based on our recent discovery that bromoallenes can act as allyl dication equivalents in the presence of a palladium catalyst and alcohol, we investigated tandem cyclization of bromoallenes bearing a sulfamide group. It is found that some bromoallenes act as allyl dication equivalents even in the absence of a palladium(0) 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‐catalyzed reaction strongly promotes the first cyclization onto the central allenic carbon atom to afford bicyclic sulfamides containing a seven‐ or eight‐membered ring. Formation of two types of bicyclic sulfamides from single bromoallenes by simply changing the reaction conditions is also described.