title: An access to the β-anomer of 4'-thio-C-ribonucleosides: hydroboration of 1-C-aryl- or 1-C-heteroaryl-4-thiofuranoid glycals and its regiochemical outcome.
abstract: We have developed a novel method for the synthesis of the β-anomer of 4'-thio-C-ribonucleosides from 3,5-O-(di-tert-butylsilylene)-4-thiofuranoid glycal. Palladium-catalyzed coupling of 1-tributylstannyl-4-thiofuranoid glycal with iodobenzene or a heteroaryl halide gave 1-C-phenyl- or 1-C-heteroaryl-glycals. Hydroboration of these glycals proceeded at the α-face, and subsequent alkaline hydrogen peroxide treatment of the resulting 2'-α-borane furnished the respective β-anomer of 4'-thio-C-ribonucleosides. These results demonstrate that this synthetic method has a wider scope in terms of heterocyclic base structure. During this study, unexpected Markovnikov-oriented hydroboration has been observed to lead to the respective 1'-α-boranes. These 1'-boranes were converted into either the ring-opened structure or the 2'-deoxy derivatives depending upon their stability.
authors.affiliation: School of Pharmacy, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan. harakazu@pharm.showa-u.ac.jp
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Haraguchi
authors.forename: Chikafumi
authors.initials: C
authors.lastname: Horii
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Yoshimura
authors.forename: Fumiko
authors.initials: F
authors.lastname: Ariga
authors.forename: Aya
authors.initials: A
authors.lastname: Tadokoro
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Tanaka
mesh_terms: D001880:Boranes / Q000737:chemistry*; D002384:Catalysis; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry; D012263:Ribonucleosides / Q000138:chemical synthesis* / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry*; D013237:Stereoisomerism; D013872:Thionucleosides / Q000138:chemical synthesis* / Q000737:chemistry*; D013876:Thiophenes / Q000737:chemistry*
chemical_list: C476353:4-thiofuranoid glycal; D001880:Boranes; D012263:Ribonucleosides; D012833:Siloxanes; D013872:Thionucleosides; D013876:Thiophenes; D010165:Palladium