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Mechanistic Details of Asymmetric Bromocyclization with BINAP Monoxide: Identification of Chiral Proton-Bridged Bisphosphine Oxide Complex and Its Application to Parallel Kinetic Resolution.
Yamashita, Kenji; Hirokawa, Ryo; Ichikawa, Mamoru; Hisanaga, Tatsunari; Nagao, Yoshihiro; Takita, Ryo; Watanabe, Kohei; Kawato, Yuji; Hamashima, Yoshitaka.
Afiliación
  • Yamashita K; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
  • Hirokawa R; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
  • Ichikawa M; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
  • Hisanaga T; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
  • Nagao Y; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
  • Takita R; Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
  • Watanabe K; Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
  • Kawato Y; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
  • Hamashima Y; School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
J Am Chem Soc ; 144(9): 3913-3924, 2022 03 09.
Article en En | MEDLINE | ID: mdl-35226811
The mechanism of our previously reported catalytic asymmetric bromocyclization reactions using 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (BINAP) monoxide was examined in detail by the means of control experiments, NMR studies, X-ray structure analysis, and CryoSpray electrospray ionization mass spectrometry (ESI-MS) analysis. The chiral BINAP monoxide was transformed to a key catalyst precursor, proton-bridged bisphosphine oxide complex (POHOP·Br), in the presence of N-bromosuccinimide (NBS) and contaminating water. The thus-formed POHOP further reacts with NBS to afford BINAP dioxide and molecular bromine (Br2) simultaneously in equimolar amounts. While the resulting Br2 is activated by NBS to form a more reactive brominating reagent (Br2─NBS), BINAP dioxide serves as a bifunctional catalyst, acting as both a Lewis base that reacts with Br2─NBS to form a chiral brominating agent (P═O+─Br) and also as a Brønsted base for the activation of the substrate. By taking advantage of this novel concerted Lewis/Brønsted base catalysis by BINAP dioxide, we achieved the first regio- and chemodivergent parallel kinetic resolutions (PKRs) of racemic unsymmetrical bisallylic amides via bromocyclization.
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Óxidos / Protones Tipo de estudio: Diagnostic_studies Idioma: En Revista: J Am Chem Soc Año: 2022 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Estados Unidos
Texto completo
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Texto completo: 1 Colección: 01-internacional Base de datos: MEDLINE Asunto principal: Óxidos / Protones Tipo de estudio: Diagnostic_studies Idioma: En Revista: J Am Chem Soc Año: 2022 Tipo del documento: Article País de afiliación: Japón Pais de publicación: Estados Unidos