Koki Fujimura

National Institute of Advanced Industrial Science and Technology

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Y. Ueda

Kyoto University

Takeo Kawabata

International University of Health and Welfare

Kiyosei Takasu

Kyoto University

Naruhiro Gondo

Kyoto University Institute for Chemical Research

Yousuke Yamaoka

Hyogo University

Ryuichi Hyakutake

Kyoto University Institute for Chemical Research

Yoshifumi Hashikawa

Kyoto Bunkyo University

Masahiro Yamanaka

Rigaku (Japan)

Katsuhiko Nakano

Rikkyo University

Ryosuke Tsutsumi

Keio University

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Kyoto University

Kyoto University Institute for Chemical Research

Kyoto Bunkyo University

Osaka University

Tohoku University

Instituto de Investigaciones Químicas

The University of Tokyo

Rikkyo University

National Institute of Advanced Industrial Science and Technology

Catalytic Materials (United States)

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Front Cover: Catalyst‐Dependent Rate‐Determining Steps in Regiodivergent Vinylogous Aza‐Morita‐Baylis‐Hillman Reactions with N‐Ts Imines (Asian J. Org. Chem. 3/2022)

Asian Journal of Organic Chemistry (2022)

Naruhiro Gondo Ryuichi Hyakutake Koki Fujimura Y. Ueda Katsuhiko Nakano

The mechanistic analysis of catalyst-controlled regiodivergent aza-Morita-Baylis-Hillman reactions of vinylcyclopentenone is described. DABCO-catalyzed reaction gives the α-adduct exclusively (red reaction) and DMAP-catalyzed reaction produces the γ-adduct selectively (blue reaction). The analysis revealed that the rate-determining step (RDS) of the DABCO-catalyzed α-selective reactions is the Mannich-type C−C bond formation step, whereas the RDS of the DMAP-catalyzed γ-selective reactions seems to be the β-elimination step. More information can be found in the Full Paper by Yoshihiro Ueda, Masahiro Yamanaka, Takeo Kawabata et al.

DABCO

Baylis–Hillman reaction

10.1002/ajoc.202200033

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Rotaxane Synthesis by an End‐Capping Strategy via Swelling Axle‐Phenols

Angewandte Chemie International Edition (2023)

Koki Fujimura Y. Ueda Yousuke Yamaoka Kiyosei Takasu Takeo Kawabata

A method for rotaxane synthesis by enlargement of the size of the terminal phenol group of the axle component by aromatic bromination has been developed. This method may be regarded as an end-capping strategy involving the swelling of the phenol group at the axle terminal. The advantages of the present strategy include: ready availability of axle components with a variety of swelling precursors, wide product scope (19 examples given including a [3]rotaxane), mild conditions for the swelling process, rich potential for the derivatization of the brominated rotaxanes, and possible release of the axle component by degradative dethreading of the thermally stable brominated rotaxanes under the basic conditions.

Rotaxane

10.1002/anie.202303078

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CCDC 2069935: Experimental Crystal Structure Determination

The Cambridge Structural Database (2023)

Naruhiro Gondo Koki Fujimura Ryuichi Hyakutake Y. Ueda Takeo Kawabata

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

10.5517/ccdc.csd.cc27gy3s

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CCDC 2238333: Experimental Crystal Structure Determination

The Cambridge Structural Database (2023)

Koki Fujimura Y. Ueda Yousuke Yamaoka Kiyosei Takasu Takeo Kawabata

10.5517/ccdc.csd.cc2f4592

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Catalytic Kinetic Resolution of Inherently Chiral Open-Caged Fullerene Derivative

The Pharmaceutical Society of Japan (2021)

Koki Fujimura

Kinetic resolution

Derivative (finance)

Source

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Organocatalytic regio- and enantioselective vinylogous aza-Morita-Baylis-Hillman reaction

Tetrahedron Letters (2022)

Naruhiro Gondo Koki Fujimura Ryuichi Hyakutake Y. Ueda Takeo Kawabata

Aldimine

Baylis–Hillman reaction

10.1016/j.tetlet.2022.154306

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Chiroptical Response of Carbon Nanocages Enhanced by Achiral Guests

Angewandte Chemie (2024)

Yoshifumi Hashikawa Koki Fujimura Y. Ueda Norihisa Fukaya Takeo Kawabata

Opening up [60]fullerene makes itself inherently chiral without loss of congenital π‐conjugation. An immoderately large aperture on [60]fullerene, however, renders the molecule less rigid and therefore it would reduce dissymmetry factors. Herein, we examined supramolecular technique in geometrical reinforcement of chiral open‐[60]fullerenes by encasing achiral guests such as Ar,‐CO2, and CH3CN. At a lowest‐energy transition, we confirmed a guest‐dependency on chiroptical responses with increasing a dissymmetry factor by nearly twice to three times. It should be noted that the guests play a negligible role in electronic structures of the carbon cages. Instead, they are engaged in preclusion of an orifice shrinking not to reduce chiroptical response.

Nanocages

Carbon fibers

10.1002/ange.202421859

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Approach Toward Reversal of Chemoselectivity in Catalytic Silylation of Pyranosides

European Journal of Organic Chemistry (2022)

Hashimoto Hisashi Y. Ueda Koki Fujimura Kiyosei Takasu Takeo Kawabata

Abstract It is widely recognized that primary hydroxy groups show much higher reactivity than the secondary ones, especially in trialkylsilylation. Actually, DMAP‐catalyzed silylation of unprotected pyranosides gave the 6‐ O ‐silylate exclusively by silylation of the primary C(6)−OH. On the other hand, catalyst ent ‐ C1 overcame the general tendency of silylation, and enabled the selective silylation of the secondary C(3)−OH of two β‐glucopyranosides and a β‐galactopyranoside. Although the yields of the silylation are poor at this stage, this is the first example of selective silylation of the secondary hydroxy group in the presence of the free primary C(6)−OH of pyranosides under the catalyst‐controlled conditions.

Chemoselectivity

Primary (astronomy)

Reactivity

10.1002/ejoc.202200949

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CCDC 2238334: Experimental Crystal Structure Determination

The Cambridge Structural Database (2023)

Koki Fujimura Y. Ueda Yousuke Yamaoka Kiyosei Takasu Takeo Kawabata

10.5517/ccdc.csd.cc2f45b3

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Rotaxane Synthesis by an End‐Capping Strategy via Swelling Axle‐Phenols

Angewandte Chemie (2023)

Koki Fujimura Y. Ueda Yousuke Yamaoka Kiyosei Takasu Takeo Kawabata

Abstract A method for rotaxane synthesis by enlargement of the size of the terminal phenol group of the axle component by aromatic bromination has been developed. This method may be regarded as an end‐capping strategy involving the swelling of the phenol group at the axle terminal. The advantages of the present strategy include: ready availability of axle components with a variety of swelling precursors, wide product scope (19 examples given including a [3]rotaxane), mild conditions for the swelling process, rich potential for the derivatization of the brominated rotaxanes, and possible release of the axle component by degradative dethreading of the thermally stable brominated rotaxanes under the basic conditions.

Rotaxane

10.1002/ange.202303078

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