Patents by Inventor Tsuneo Imamoto

Tsuneo Imamoto has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 7534920
    Abstract: An optically-active bis(alkynylphosphino)ethane-borane derivative represented by formula (1): wherein R1 and R2, which may be the same or different, each represent an alkyl group, a phenyl group, an alkylsilyl group or a hydrogen atom; R3 represents a branched alkyl group, an alicyclic hydrocarbon group or an aromatic hydrocarbon group; and the asterisk * indicates an optically-active site. The derivative (1) is prepared by bromination of, e.g., an (S)-t-butylmethylphosphine-borane, reaction with an alkynyl lithium, deprotonation, followed by oxidative coupling. Deprotection of the derivative (1) by deboranation gives an optically-active bis(alkynylphosphino)ethane derivative useful as a ligand providing an asymmetric catalyst for catalytic asymmetric synthesis. The asymmetric catalyst having the ligand exhibits high selectivity and catalyst activity.
    Type: Grant
    Filed: March 5, 2008
    Date of Patent: May 19, 2009
    Assignees: Nippon Chemical Industrial Co., Ltd., National University Corporation Chiba University
    Inventors: Tsuneo Imamoto, Kazuhiro Yoshida, Youichi Saitoh, Aya Koide
  • Publication number: 20090062567
    Abstract: The present invention aims to provide a bis(phosphine) boronium salt to be used as a building block or the like for producing a diphosphine compound effective mainly for various kinds of transition metal-catalyzed reactions and further to provide a preferable production method of the bis(phosphine) boronium salt and a bis(phosphine) boronium salt to be produced by the production method. The present invention provides a bis(phosphine) boronium salt having the structure defined by the following formula (1).
    Type: Application
    Filed: January 30, 2007
    Publication date: March 5, 2009
    Applicants: Japan Science and Technology Agency, National University Corporation Chiba University
    Inventors: Kentaro Yamaguchi, Hiroshi Danjo, Toru Koizumi, Tsuneo Imamoto
  • Publication number: 20090030200
    Abstract: Disclosed is a process of preparing an optically active allyl compound comprising asymmetrically coupling an allyl compound with an organic nucleophilic compound in the presence of a catalyst. The catalyst is preferably a transition metal complex compound having a phosphine ligand. The phosphine ligand is preferably a 2,3-bis(dialkylphosphino)pyrazine derivative. The pyrazine derivative is preferably a quinoxaline derivative. The transition metal is preferably palladium.
    Type: Application
    Filed: July 24, 2008
    Publication date: January 29, 2009
    Applicants: NATIONAL UNIVERSITY CORPORATION CHIBA UNIVERSITY, NIPPON CHEMICAL INDUSTRIAL CO., LTD.
    Inventors: Tsuneo IMAMOTO, Kazuhiro YOSHIDA, Miwako NISHIMURA, Aya KOIDE
  • Publication number: 20090030231
    Abstract: Disclosed is a process of preparing an optically active ?-hydroxycarboxylic acid derivative comprising asymmetrically hydrogenating a ?-keto compound in the presence of a catalyst comprising a transition metal complex compound having a 2,3-bis(dialkylphosphino)pyrazine derivative as a ligand. The pyrazine derivative is preferably a quinoxaline derivative, and the transition metal is preferably ruthenium. Preferred examples of the quinoxaline derivative are (S,S)-2,3-bis(tert-butylmethylphosphino)quinoxaline, (R,R)-bis(tert-butylmethylphosphino)quinoxaline, (S,S)-bis(tert-adamantylmethylphosphino)quinoxaline, and (R,R)-bis(adamantylmethylphosphino)quinoxaline.
    Type: Application
    Filed: July 24, 2008
    Publication date: January 29, 2009
    Applicants: NATIONAL UNIVERSITY CORPORATION CHIBA UNIVERSITY, NIPPON CHEMICAL INDUSTRIAL CO., LTD.
    Inventors: Tsuneo IMAMOTO, Kazuhiro YOSHIDA, Miwako NISHIMURA, Aya KOIDE
  • Publication number: 20080221362
    Abstract: An optically-active bis(alkynylphosphino)ethane-borane derivative represented by formula (1): wherein R1 and R2, which may be the same or different, each represent an alkyl group, a phenyl group, an alkylsilyl group or a hydrogen atom; R3 represents a branched alkyl group, an alicyclic hydrocarbon group or an aromatic hydrocarbon group; and the asterisk * indicates an optically-active site. The derivative (1) is prepared by bromination of, e.g., an (S)-t-butylmethylphosphine-borane, reaction with an alkynyl lithium, deprotonation, followed by oxidative coupling. Deprotection of the derivative (1) by deboranation gives an optically-active bis(alkynylphosphino)ethane derivative useful as a ligand providing an asymmetric catalyst for catalytic asymmetric synthesis. The asymmetric catalyst having the ligand exhibits high selectivity and catalyst activity.
    Type: Application
    Filed: March 5, 2008
    Publication date: September 11, 2008
    Applicants: Nippon Chemical Industrial Co., Ltd., National University Corporation Chiba University
    Inventors: Tsuneo Imamoto, Kazuhiro Yoshida, Youichi Saitoh, Aya Koide
  • Patent number: 7411096
    Abstract: The present invention provides a process for producing an optically active phosphorus heterocyclic dimer including reacting, in the presence of a base, primary phosphine represented by formula (1) R—PH2 ??(1) is reacted with a compound represented by formula (2) Y—CnH2n—Y ??(2) in the presence of a base; the product is reacted with boron trihydride, oxygen, or sulfur to obtain a phosphorus heterocyclic compound represented by formula (3): the resultant compound is dimerized to produce a phosphorus heterocyclic dimer represented by formula (4): and then oxygen, sulfur, or borane is removed from the resultant phosphorus heterocyclic dimer to obtain an optically active phosphorus heterocyclic dimer represented by formula (5):
    Type: Grant
    Filed: July 27, 2004
    Date of Patent: August 12, 2008
    Assignee: Nippon Chemical Industrial Co., Ltd.
    Inventors: Nobuhiko Oohara, Tsuneo Imamoto
  • Publication number: 20070021610
    Abstract: An optically active 2,3-bis(dialkylphosphino)pyrazine derivative represented by formula (1) is disclosed. The pyrazine derivative is preferably a quinoxaline derivative represented by formula (2). In formula (1) and (2), R1 is preferably a t-butyl or adamantyl group, and R2 is preferably a methyl group. wherein R1 is a substituted or unsubstituted, straight chain or branched alkyl group having 2 to 10 carbon atoms; R2 is a substituted or unsubstituted, straight chain or branched alkyl group having fewer carbon atoms than R1; and R3 and R4, which may be the same or different, are each a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, or R3 and R4 are taken together to form a saturated or unsaturated ring. wherein R1 and R2 are as defined above; and R5 is a monovalent substituent.
    Type: Application
    Filed: February 23, 2006
    Publication date: January 25, 2007
    Inventors: Tsuneo Imamoto, Kazuhiro Yoshida, Keitaro Sugita
  • Publication number: 20060211888
    Abstract: Primary phosphine represented by formula (1): [Chem. 1] R—PH2??(1) (wherein R represents a linear, branched, or cyclic alkyl group having 2 to 20 carbon atoms) is reacted with a compound represented by formula (2): [Chem.
    Type: Application
    Filed: July 27, 2004
    Publication date: September 21, 2006
    Inventors: Nobuhiko Oohara, Tsuneo Imamoto
  • Publication number: 20060189818
    Abstract: The present invention provides a novel optically active phosphorus-chiral diphosphetane compound useful as a ligand of a transition metal catalyst which is used for catalytic asymmetric synthesis such as asymmetric hydrogenation reaction and the like, the ligand capable of creating a stable asymmetric space when coordinating to a central metal, an intermediate of the compound, and a transition metal complex catalyst having the compound as a ligand. The optically active diphosphetane compound of the present invention has a structure represented by formula (1): (wherein R represents a linear, branched, or cyclic alkyl group having 2 to 20 carbon atoms).
    Type: Application
    Filed: July 27, 2004
    Publication date: August 24, 2006
    Inventors: Nobuhiko Oohara, Tsuneo Imamoto
  • Patent number: 6194593
    Abstract: An optically active 1,2-bis(dialkylphosphino) benzene derivative represented by the general formula (1) which is suitable as a ligand for a transition metal catalyst in asymmetrical hydrogenation is provided. Also provided is a process for producing such a benzene derivative, and a rhodium metal complex having such a benzene derivative as a ligand which is useful as an asymmetric catalyst for use in asymmetrical hydrogenation. (where R1 denotes a straight or branched alkyl group having 2-6 carbon atoms, and each of the asterisks denotes an asymmetric phosphorus atom).
    Type: Grant
    Filed: January 28, 2000
    Date of Patent: February 27, 2001
    Assignee: Nippon Chemical Industrial Co., Ltd.
    Inventors: Tsuneo Imamoto, Tomoya Miura, Hironari Yamada