title: Tris(pentafluorophenyl)borane-Catalyzed Acceptorless Dehydrogenation of N-Heterocycles.
abstract: Catalytic acceptorless dehydrogenation is an environmentally benign way to desaturate organic compounds. This process is traditionally accomplished with transition-metal-based catalysts. Herein, a borane-catalyzed, metal-free acceptorless dehydrogenation of saturated N-heterocycles is disclosed. Tris(pentafluorophenyl)borane was identified as a versatile catalyst, which afforded several synthetically important N-heteroarenes in up to quantitative yield. Specifically, the present metal-free catalytic system exhibited a uniquely high tolerance toward sulfur functionalities, and demonstrated superior reactivity in the synthesis of benzothiazoles compared to conventional metal-catalyzed systems. This protocol can thus be regarded as the first example of metal-free acceptorless dehydrogenation in synthetic organic chemistry.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kojima
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. kanai@mol.f.u-tokyo.ac.jp.|Japan Science and Technology Agency, ERATO, Kanai Life Science Catalysis Project, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan. kanai@mol.f.u-tokyo.ac.jp.
authors.forename: Motomu
authors.initials: M
authors.lastname: Kanai
keywords: boron; heterocycles; homogeneous catalysis; hydrogen; synthetic methods