title: 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.
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.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Hamaguchi
authors.forename: Shohei
authors.initials: S
authors.lastname: Kosaka
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Ohno
authors.forename: Nobutaka
authors.initials: N
authors.lastname: Fujii
authors.forename: Tetsuaki
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000466:Alkadienes / Q000737:chemistry*; D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis*; D001966:Bromine / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D008956:Models, Chemical; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism; D013449:Sulfonamides / Q000138:chemical synthesis*
chemical_list: D000466:Alkadienes; D001643:Bridged Bicyclo Compounds; D013449:Sulfonamides; C025947:propadiene; D010165:Palladium; D001966:Bromine