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  1. Article ; Online: Diarylprolinol as an Effective Organocatalyst in Asymmetric Cross-Aldol Reactions of Two Different Aldehydes.

    Hayashi, Yujiro

    Chemical record (New York, N.Y.)

    2022  Volume 23, Issue 7, Page(s) e202200159

    Abstract: The aldol reaction is one of the most important carbon-carbon bond-forming reactions in organic chemistry. Asymmetric direct cross-aldol reaction of two different aldehydes has been regarded as a difficult reaction because of the side reactions such as ... ...

    Abstract The aldol reaction is one of the most important carbon-carbon bond-forming reactions in organic chemistry. Asymmetric direct cross-aldol reaction of two different aldehydes has been regarded as a difficult reaction because of the side reactions such as self-aldol reaction and over reaction. We found that trifluoromethyl-substituted diarylprolinol, α,α-bis[3,5-bis(trifluoromethyl)phenyl]-2-pyrrolidinemethanol (1), is an effective organocatalyst that promotes several cross-aldol reactions of aldehydes with excellent diastereo- and enantioselectivities. Acetaldehyde can be employed as a suitable nucleophilic aldehyde. Successful electrophilic aldehydes are ethyl glyoxylate, chloroacetaldehyde, dichloroacetaldehyde, chloral, α-alkyl-α-oxo aldehyde, trifluoroacetaldehyde, glyoxal, alkenyl aldehyde, alkynyl aldehyde, and formaldehyde. Some of the aldehydes are commercially available as a polymer solution, an aqueous solution, or in the hydrated form. They can be used directly in the asymmetric aldol reaction as a commercially available form, which is a synthetic advantage. Given that the obtained aldol products possess several functional groups along with a formyl moiety, they are synthetically useful chiral building blocks.
    MeSH term(s) Catalysis ; Aldehydes ; Water ; Carbon
    Chemical Substances 3-hydroxybutanal (8C6G962B53) ; Aldehydes ; Water (059QF0KO0R) ; Carbon (7440-44-0)
    Language English
    Publishing date 2022-07-27
    Publishing country United States
    Document type Journal Article ; Review
    ZDB-ID 2044646-9
    ISSN 1528-0691 ; 1527-8999
    ISSN (online) 1528-0691
    ISSN 1527-8999
    DOI 10.1002/tcr.202200159
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  2. Article ; Online: Time and Pot Economy in Total Synthesis.

    Hayashi, Yujiro

    Accounts of chemical research

    2021  Volume 54, Issue 6, Page(s) 1385–1398

    Abstract: We would all like to make or obtain the materials or products we want as soon as possible. This is human nature. This is true also for chemists in the synthesis of organic molecules. All chemists would like to make their target molecules as soon as ... ...

    Abstract We would all like to make or obtain the materials or products we want as soon as possible. This is human nature. This is true also for chemists in the synthesis of organic molecules. All chemists would like to make their target molecules as soon as possible, particularly when their interest is in the physical or biological properties of those molecules.As demonstrated by today's COVID-19 (SARS-CoV-2) pandemic, rapid synthesis is also crucial to enable chemists to deliver effective therapeutic agents to the community. Several concepts are currently well-accepted as important for achieving this: atom economy, step economy, and redox economy. Considering the importance of synthesizing organic molecules rapidly, I recently proposed adding the concept of time economy.In a multisep synthesis, each step has to be completed within a short period of time to make the desired molecule rapidly. The development of rapid reactions is important but also insufficient. After each step, frequent and repetitive workup operations such as quenching the reaction, extraction, separation of water and organic phases, drying the organic phase, filtration, evaporation, and purification may be required, and the time necessary for these processing operations must be taken into account. Indeed, some of the most time-consuming operations in most syntheses are the purification stages.On the other hand, one-pot reactions are processes in which several sequential reactions are conducted in a single reaction vessel, which avoids the need to purify intermediates. One-pot reactions are a useful way to shorten the total synthesis time, and the approach generally leads to an increase in the yield and a reduction in the amount of chemical waste formed. Thus, I also propose the importance of pot economy.On the basis of these concepts of time and pot economy, we have accomplished efficient syntheses of several natural products and medicines. The key to the success of these syntheses is the use of diphenylprolinol silyl ether as an effective catalyst in a one-pot reaction, in which it does not disturb the subsequent reactions. Our strategy is (1) to construct the chiral key skeletons and/or key components of natural products and medicines directly using organocatalyst-mediated one-pot reactions and (2) to conduct the subsequent transformations to the final molecules in a small number of pots utilizing the internal quench method. By means of this strategy, PGE
    Language English
    Publishing date 2021-02-22
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1483291-4
    ISSN 1520-4898 ; 0001-4842
    ISSN (online) 1520-4898
    ISSN 0001-4842
    DOI 10.1021/acs.accounts.0c00803
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Time Economy in Total Synthesis.

    Hayashi, Yujiro

    The Journal of organic chemistry

    2020  Volume 86, Issue 1, Page(s) 1–23

    Abstract: It is often said that "time is money". This is certainly true in a multistep synthesis when a high-valued product or set of products is needed urgently. Fulfilling this need requires the sensible balancing of atom economy, step economy, and redox economy ...

    Abstract It is often said that "time is money". This is certainly true in a multistep synthesis when a high-valued product or set of products is needed urgently. Fulfilling this need requires the sensible balancing of atom economy, step economy, and redox economy with the time taken to make the product. In this age of flu-based pandemics, the need for rapid provision of effective therapeutic agents makes the importance of "time economy" particularly clear. In this Perspective, the importance of time economy in total synthesis is described, as well as the general considerations underlining the timely production of desired molecules. As case studies, the syntheses of Tamiflu, Corey lactone, and ibuprofen are discussed, with emphasis on comparing classical and contemporary approaches to a rapid total synthesis. By using modern tactics such as one-pot reaction procedures and versatile synthetic methodologies such as organocatalyst mediated domino reactions coupled with strict-control technologies such as flow chemistry, Tamiflu and Corey lactone can now be synthesized within 60 and 152 min, respectively, using one vessel via a batch system. Tamiflu and ibuprofen can be prepared via flow system, and their total residence times are 11.5 and 3 min, respectively.
    MeSH term(s) Oxidation-Reduction
    Language English
    Publishing date 2020-10-21
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/acs.joc.0c01581
    Database MEDical Literature Analysis and Retrieval System OnLINE

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    In stock of ZB MED Cologne/Königswinter

    Zs.A 4473: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (2.OG)
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  4. Article ; Online: STUDIES ON MUSCLE DIFFERENTIATION. V. ANTIGENICITIES OF MYOSIN AND OF ACTIN FROM FROG SKELETAL MUSCLES

    Hirabayashi, Tamio / Hayashi, Yujiro

    Development, growth & differentiation

    2023  Volume 14, Issue 2, Page(s) 133–164

    Abstract: Both intact and denatured preparations of myosin and actin from frog skeletal muscles produced in rabbits antisera containing antibodies against authentic myosin and actin, respectively, though being contaminated with antibodies against other proteins. ... ...

    Abstract Both intact and denatured preparations of myosin and actin from frog skeletal muscles produced in rabbits antisera containing antibodies against authentic myosin and actin, respectively, though being contaminated with antibodies against other proteins. Antigenicity of our frog myosin as revealed in agar diffusion tests was indistinguishable from that of cardiac muscle myosin from the same species. Similarly, skeletal muscle myosins from other amphibians shared to a certain extent immunological characteristics with our frog myosin, but those from avian and mammalian materials did not. Similarity in antigenicity was also demonstrated among our skeletal muscle actin, cardiac muscle actin from the same species and skeletal muscle actin from the other anurans studied. However, skeletal muscle actin from an urodele could not clearly be correlated in its immunological properties with our frog actin, and those from avian and mammalian materials were antigenically different from our frog actin. Thus, the degree of antigenic similarity of these muscle proteins seemed to be correlated with the phylogenic relationship of the animals so far studied. The results also indicated that our antisera could only be applied to immuno-cytological and immuno-embryological studies of myosin and actin when the antisera absorbed with the corresponding antigen preparations were used as negative controls.
    Language English
    Publishing date 2023-06-06
    Publishing country Japan
    Document type Journal Article
    ZDB-ID 280433-5
    ISSN 1440-169X ; 0012-1592
    ISSN (online) 1440-169X
    ISSN 0012-1592
    DOI 10.1111/j.1440-169X.1972.00133.x
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    In stock of ZB MED Cologne/Königswinter

    Zs.A 194: Show issues Location:
    Je nach Verfügbarkeit (siehe Angabe bei Bestand)
    bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular
    Jg. 1995 - 2021: Lesesall (1.OG)
    ab Jg. 2022: Lesesaal (EG)

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  5. Article: Organocatalyst-mediated asymmetric one-pot/two domino/three-component coupling reactions for the synthesis of

    Mori, Naoki / Tachibana, Toshiki / Umekubo, Nariyoshi / Hayashi, Yujiro

    Chemical science

    2024  Volume 15, Issue 15, Page(s) 5627–5632

    Abstract: ... Highly ... ...

    Abstract Highly substituted
    Language English
    Publishing date 2024-03-12
    Publishing country England
    Document type Journal Article
    ZDB-ID 2559110-1
    ISSN 2041-6539 ; 2041-6520
    ISSN (online) 2041-6539
    ISSN 2041-6520
    DOI 10.1039/d4sc00193a
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Time Economy in Total Synthesis

    Hayashi, Yujiro

    Journal of organic chemistry. 2020 Oct. 21, v. 86, no. 1

    2020  

    Abstract: It is often said that “time is money”. This is certainly true in a multistep synthesis when a high-valued product or set of products is needed urgently. Fulfilling this need requires the sensible balancing of atom economy, step economy, and redox economy ...

    Abstract It is often said that “time is money”. This is certainly true in a multistep synthesis when a high-valued product or set of products is needed urgently. Fulfilling this need requires the sensible balancing of atom economy, step economy, and redox economy with the time taken to make the product. In this age of flu-based pandemics, the need for rapid provision of effective therapeutic agents makes the importance of “time economy” particularly clear. In this Perspective, the importance of time economy in total synthesis is described, as well as the general considerations underlining the timely production of desired molecules. As case studies, the syntheses of Tamiflu, Corey lactone, and ibuprofen are discussed, with emphasis on comparing classical and contemporary approaches to a rapid total synthesis. By using modern tactics such as one-pot reaction procedures and versatile synthetic methodologies such as organocatalyst mediated domino reactions coupled with strict-control technologies such as flow chemistry, Tamiflu and Corey lactone can now be synthesized within 60 and 152 min, respectively, using one vessel via a batch system. Tamiflu and ibuprofen can be prepared via flow system, and their total residence times are 11.5 and 3 min, respectively.
    Keywords batch systems ; ibuprofen ; organic chemistry ; organocatalysts ; oseltamivir ; therapeutics
    Language English
    Dates of publication 2020-1021
    Size p. 1-23.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 123490-0
    ISSN 1520-6904 ; 0022-3263
    ISSN (online) 1520-6904
    ISSN 0022-3263
    DOI 10.1021/acs.joc.0c01581
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    In stock of ZB MED Bonn / Germany

    Z 4' 49/42: Show issues
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  7. Article ; Online: Organocatalyst-mediated five-pot synthesis of (-)-quinine.

    Terunuma, Takahiro / Hayashi, Yujiro

    Nature communications

    2022  Volume 13, Issue 1, Page(s) 7503

    Abstract: In this work, the enantioselective total synthesis of (-)-quinine has been accomplished in a pot-economical manner using five reaction vessels. In the first pot, reactions involve the diphenylprolinol silyl ether-mediated Michael reaction, aza-Henry ... ...

    Abstract In this work, the enantioselective total synthesis of (-)-quinine has been accomplished in a pot-economical manner using five reaction vessels. In the first pot, reactions involve the diphenylprolinol silyl ether-mediated Michael reaction, aza-Henry reaction, hemiaminalization, and elimination of HNO
    MeSH term(s) Quinine
    Chemical Substances Quinine (A7V27PHC7A)
    Language English
    Publishing date 2022-12-07
    Publishing country England
    Document type Journal Article
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-022-34916-z
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  8. Article ; Online: Catalytic Asymmetric Michael Reaction of Methyl Alkynyl Ketone Catalyzed by Diphenylprolinol Silyl Ether.

    Umekubo, Nariyoshi / Hayashi, Yujiro

    ACS organic & inorganic Au

    2022  Volume 2, Issue 3, Page(s) 245–251

    Abstract: The asymmetric Michael reaction of methyl alkynyl ketone and α,β-unsaturated aldehyde catalyzed by diphenylprolinol silyl ether was developed. Although methyl alkynyl ketone is a good Michael acceptor, it also acts as a Michael donor to afford the ... ...

    Abstract The asymmetric Michael reaction of methyl alkynyl ketone and α,β-unsaturated aldehyde catalyzed by diphenylprolinol silyl ether was developed. Although methyl alkynyl ketone is a good Michael acceptor, it also acts as a Michael donor to afford the synthetically important δ-oxo aldehydes with excellent enantioselectivity. The products possessing several functional groups, such as alkyne, ketone, and aldehyde moieties, are useful chiral building blocks for further synthesis. Using this reaction as a key step, a side chain of atorvastatin (Lipitor), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, was synthesized in a two-pot sequence with excellent diastereo- and enantioselectivities.
    Language English
    Publishing date 2022-01-26
    Publishing country United States
    Document type Journal Article
    ISSN 2694-247X
    ISSN (online) 2694-247X
    DOI 10.1021/acsorginorgau.1c00054
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  9. Article: Organocatalyst-mediated, pot-economical total synthesis of latanoprost.

    Kawauchi, Genki / Suga, Yurina / Toda, Shunsuke / Hayashi, Yujiro

    Chemical science

    2023  Volume 14, Issue 37, Page(s) 10081–10086

    Abstract: The enantioselective total synthesis of latanoprost, an antiglaucoma agent, has been accomplished with excellent diastereo- and enantioselectivities in a pot-economical manner using six reaction vessels. An enantioselective Krische allylation was ... ...

    Abstract The enantioselective total synthesis of latanoprost, an antiglaucoma agent, has been accomplished with excellent diastereo- and enantioselectivities in a pot-economical manner using six reaction vessels. An enantioselective Krische allylation was conducted in the first pot. In the second pot, olefin metathesis, silyl protection, and hydrogenolysis proceeded efficiently. In the third pot, an organocatalyst-mediated Michael reaction proceeded with excellent diastereoselectivity. The fourth pot involved a substrate-controlled Mukaiyama intramolecular aldol reaction and elimination of HNO
    Language English
    Publishing date 2023-08-01
    Publishing country England
    Document type Journal Article
    ZDB-ID 2559110-1
    ISSN 2041-6539 ; 2041-6520
    ISSN (online) 2041-6539
    ISSN 2041-6520
    DOI 10.1039/d3sc02978f
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: The emergence of super-resolution beyond the probe size in scanning 3DXRD microscopy.

    Kim, Jaemyung / Hayashi, Yujiro / Yabashi, Makina

    Journal of synchrotron radiation

    2023  Volume 30, Issue Pt 6, Page(s) 1108–1113

    Abstract: The spatial resolution in scanning-based two-dimensional microscopy is normally limited by the size of the probe, thereby a smaller probe is a prerequisite for enhancing the spatial resolution. For three-dimensional microscopy that combines translation ... ...

    Abstract The spatial resolution in scanning-based two-dimensional microscopy is normally limited by the size of the probe, thereby a smaller probe is a prerequisite for enhancing the spatial resolution. For three-dimensional microscopy that combines translation and rotation motions of a specimen, however, complex trajectories of the probe highly overlap in the specimen, which could change the postulate above. Here, the spatial resolution achieved in scanning three-dimensional X-ray diffraction (s3DXRD) microscopy is investigated. In this method, the most appropriate orientation of the pixel in the specimen coordinate is selected by comparing the completeness of diffraction peaks with theory. Therefore, the superposed area of the beam trajectory has a strong effect on the spatial resolution, in terms of the completeness of diffraction peaks. It was found that the highly superposed area by the incident X-rays, which has the highest completeness factor in the pixel of the specimen, is much smaller than the X-ray probe size, and that sub-pixel analysis by dividing a pixel into small pieces leads to drastic improvement of the spatial resolution in s3DXRD.
    Language English
    Publishing date 2023-10-17
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2021413-3
    ISSN 1600-5775 ; 0909-0495
    ISSN (online) 1600-5775
    ISSN 0909-0495
    DOI 10.1107/S1600577523008597
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