1
|
Abe K, Bronner C, Hayato Y, Hiraide K, Hosokawa K, Ieki K, Ikeda M, Kameda J, Kanemura Y, Kaneshima R, Kashiwagi Y, Kataoka Y, Miki S, Mine S, Miura M, Moriyama S, Nakano Y, Nakahata M, Nakayama S, Noguchi Y, Sato K, Sekiya H, Shiba H, Shimizu K, Shiozawa M, Sonoda Y, Suzuki Y, Takeda A, Takemoto Y, Tanaka H, Yano T, Han S, Kajita T, Okumura K, Tashiro T, Tomiya T, Wang X, Yoshida S, Fernandez P, Labarga L, Ospina N, Zaldivar B, Pointon BW, Kearns E, Raaf JL, Wan L, Wester T, Bian J, Griskevich NJ, Locke S, Smy MB, Sobel HW, Takhistov V, Yankelevich A, Hill J, Lee SH, Moon DH, Park RG, Jang MC, Bodur B, Scholberg K, Walter CW, Beauchêne A, Drapier O, Giampaolo A, Mueller TA, Santos AD, Paganini P, Quilain B, Nakamura T, Jang JS, Machado LN, Learned JG, Choi K, Iovine N, Cao S, Anthony LHV, Martin D, Prouse NW, Scott M, Sztuc AA, Uchida Y, Berardi V, Catanesi MG, Radicioni E, Calabria NF, Langella A, De Rosa G, Collazuol G, Iacob F, Mattiazzi M, Ludovici L, Gonin M, Pronost G, Fujisawa C, Maekawa Y, Nishimura Y, Okazaki R, Akutsu R, Friend M, Hasegawa T, Ishida T, Kobayashi T, Jakkapu M, Matsubara T, Nakadaira T, Nakamura K, Oyama Y, Sakashita K, Sekiguchi T, Tsukamoto T, Bhuiyan N, Burton GT, Di Lodovico F, Gao J, Goldsack A, Katori T, Migenda J, Xie Z, Ramsden RM, Zsoldos S, Suzuki AT, Takagi Y, Zhong H, Takeuchi Y, Feng J, Feng L, Hu JR, Hu Z, Kikawa T, Mori M, Kawaue M, Nakaya T, Wendell RA, Yasutome K, Jenkins SJ, McCauley N, Mehta P, Tarant A, Fukuda Y, Itow Y, Menjo H, Ninomiya K, Yoshioka Y, Lagoda J, Lakshmi SM, Mandal M, Mijakowski P, Prabhu YS, Zalipska J, Jia M, Jiang J, Jung CK, Wilking MJ, Yanagisawa C, Shi W, Harada M, Hino Y, Ishino H, Koshio Y, Nakanishi F, Sakai S, Tada T, Tano T, Ishizuka T, Barr G, Barrow D, Cook L, Samani S, Wark D, Holin A, Nova F, Yang BS, Yang JY, Yoo J, Jung S, Fannon JEP, Kneale L, Malek M, McElwee JM, Thiesse MD, Thompson LF, Wilson ST, Okazawa H, Kim SB, Kwon E, Seo JW, Yu I, Ichikawa AK, Nakamura KD, Tairafune S, Nishijima K, Eguchi A, Nakagiri K, Nakajima Y, Shima S, Taniuchi N, Watanabe E, Yokoyama M, de Perio P, Fujita S, Martens K, Tsui KM, Vagins MR, Xia J, Izumiyama S, Kuze M, Matsumoto R, Ishitsuka M, Ito H, Ommura Y, Shigeta N, Shinoki M, Yamauchi K, Yoshida T, Gaur R, Gousy-Leblanc V, Hartz M, Konaka A, Li X, Chen S, Xu BD, Zhang B, Posiadala-Zezula M, Boyd SB, Edwards R, Hadley D, Nicholson M, O'Flaherty M, Richards B, Ali A, Jamieson B, Amanai S, Marti L, Minamino A, Suzuki S. Search for Periodic Time Variations of the Solar ^{8}B Neutrino Flux between 1996 and 2018 in Super-Kamiokande. PHYSICAL REVIEW LETTERS 2024; 132:241803. [PMID: 38949341 DOI: 10.1103/physrevlett.132.241803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/20/2024] [Accepted: 04/12/2024] [Indexed: 07/02/2024]
Abstract
We report a search for time variations of the solar ^{8}B neutrino flux using 5804 live days of Super-Kamiokande data collected between May 31, 1996, and May 30, 2018. Super-Kamiokande measured the precise time of each solar neutrino interaction over 22 calendar years to search for solar neutrino flux modulations with unprecedented precision. Periodic modulations are searched for in a dataset comprising five-day interval solar neutrino flux measurements with a maximum likelihood method. We also applied the Lomb-Scargle method to this dataset to compare it with previous reports. The only significant modulation found is due to the elliptic orbit of the Earth around the Sun. The observed modulation is consistent with astronomical data: we measured an eccentricity of (1.53±0.35)%, and a perihelion shift of (-1.5±13.5) days.
Collapse
|
2
|
Arakawa C, Kanemoto K, Nakai K, Wang C, Morohashi S, Kwon E, Ito S, Yoshikai N. Carboiodanation of Arynes: Organoiodine(III) Compounds as Nucleophilic Organometalloids. J Am Chem Soc 2024; 146:3910-3919. [PMID: 38315817 DOI: 10.1021/jacs.3c11524] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
Organic iodine(III) compounds represent the most widely used hypervalent halogen compounds in organic synthesis, where they typically perform the role of an electrophile or oxidant to functionalize electron-rich or -nucleophilic organic compounds. In contrast to this convention, we discovered their unique reactivity as organometallic-like nucleophiles toward arynes. Equipped with diverse transferable ligands and supported by a tethered spectator ligand, the organoiodine(III) compounds undergo addition across the electrophilic C-C triple bond of arynes while retaining the trivalency of the iodine center. This carboiodanation reaction can forge a variety of aryl-alkynyl, aryl-alkenyl, and aryl-(hetero)aryl bonds along with the concurrent formation of an aryl-iodine(III) bond under mild conditions. The newly formed aryl-iodine(III) bond serves as a versatile linchpin for downstream transformations, particularly as an electrophilic reaction site. The amphoteric nature of the iodine(III) group as a metalloid and a leaving group in this sequence enables the flexible and expedient synthesis of extended π-conjugated molecules and privileged biarylphosphine ligands, where all of the iodine(III)-containing compounds can be handled as air- and thermally stable materials.
Collapse
|
3
|
Nozawa-Kumada K, Hayashi M, Kwon E, Shigeno M, Yada A, Kondo Y. Copper-Catalyzed Intramolecular Olefinic C(sp 2)-H Amidation for the Synthesis of γ-Alkylidene- γ-lactams. Molecules 2023; 28:6682. [PMID: 37764458 PMCID: PMC10537769 DOI: 10.3390/molecules28186682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/07/2023] [Accepted: 09/13/2023] [Indexed: 09/29/2023] Open
Abstract
Herein, we report the copper-catalyzed dehydrogenative C(sp2)-N bond formation of 4-pentenamides via nitrogen-centered radicals. This reaction provides a straightforward and efficient preparation method for γ-alkylidene-γ-lactams. Notably, we could controllably synthesize α,β-unsaturated- or α,β-saturated-γ-alkylidene-γ-lactams depending on the reaction conditions.
Collapse
|
4
|
Saito R, Muto T, Urano H, Kitajima T, Kato N, Kwon E, Ueda M. (3R,7S)-12-Hydroxy- jasmonoyl-L-isoleucine is the genuine bioactive stereoisomer of a jasmonate metabolite in Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023. [PMID: 37095639 DOI: 10.1111/tpj.16256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Accepted: 04/10/2023] [Indexed: 05/03/2023]
Abstract
The oxylipin plant hormone JA-Ile is widely recognized as a plant defense hormone against pathogens and chewing insects. The metabolism of JA-Ile into 12-OH-JA-Ile and 12-COOH-JA-Ile is the central mechanism for the inactivation of JA signaling. Recently, 12-OH-JA-Ile was reported to function as a ligand for the JA-Ile co-receptor COI1-JAZ. However, in previous studies, the "12-OH-JA-Ile" used was a mixture of four stereoisomers, the naturally occurring cis-isomer (3R,7S)-12-OH-JA-Ile and the trans-isomer (3R,7R)-12-OH-JA-Ile and the unnatural cis-isomer (3S,7R)-12-OH-JA-Ile and the trans-isomer (3S,7S)-12-OH-JA-Ile. Thus, the genuine bioactive form of 12-OH-JA-Ile has not yet been identified. In this study, we prepared pure stereoisomers of 12-OH-JA-Ile and identified (3R,7S)-12-OH-JA-Ile, as the naturally occurring bioactive form of 12-OH-JA-Ile and found that it binds to COI1-JAZ9 as effectively as (3R,7S)-JA-Ile. In addition, we revealed that the unnatural trans-isomer (3S,7S)-12-OH-JA-L-Ile functions as another bioactive isomer. The pure (3R,7S)-12-OH-JA-Ile causes partial JA-responsive gene expression without affecting the expressions of JAZ8/10, which are involved in the negative feedback regulation of JA-signaling. Thus, (3R,7S)-12-OH-JA-Ile could cause weak and sustainable expression of certain JA-responsive genes until the catabolism of (3R,7S)-12-OH-JA-Ile into (3R,7S)-12-COOH-JA-Ile and (3R,7S)-12-OH-JA occurs. The use of chemically pure (3R,7S)-12-OH-JA-Ile confirmed the genuine biological activities of "12-OH-JA-Ile" by excluding the possible effects of other stereoisomers. A chemical supply of pure (3R,7S)-12-OH-JA-Ile with an exact bioactivity profile will enable further detailed studies of the unique role of 12-OH-JA-Ile in planta.
Collapse
|
5
|
Bieber A, Müller K, Kools S, Hilker L, Ebner L, Kirchgässler A, Rohmann R, Kleinz T, Ortmann L, Basner L, Kühn E, Averdunk P, Schmitz F, Bulut Y, Huckemann S, Scholz L, Fisse A, Motte J, Grüter T, Kwon E, Schneider-Gold C, Gold R, Tönges L, Pitarokoili K. P-99 Nerve conduction studies in a cohort of patients with Parkinson[StQuote]s disease, multiple system atrophy and progressive supranuclear palsy. Clin Neurophysiol 2023. [DOI: 10.1016/j.clinph.2023.02.116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023]
|
6
|
Ueda H, Sato S, Noda K, Hakamata H, Kwon E, Kobayashi N, Tokuyama H. Iron-Catalyzed Biomimetic Dimerization of Tryptophan-Containing Peptides. Angew Chem Int Ed Engl 2023; 62:e202302404. [PMID: 36961091 DOI: 10.1002/anie.202302404] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/23/2023] [Accepted: 03/24/2023] [Indexed: 03/25/2023]
Abstract
Biomimetic oxidative dimerization of tryptophan derivatives in aqueous media with oxygen as a bulk oxidant catalyzed by an iron octacarboxy phthalocyanine complex was established. The discovery of the extremely active iron catalyst enables to perform aerobic enzyme-mimetic oxidation in the flask. This method was applicable to the oxidative dimerization of a wide range of tryptophan derivatives, including various dipeptides and oligopeptides with remarkable functional group tolerance without the protection of the amino acid residues. Furthermore, oxidative dimerization of tryptophan derivatives bearing dioxopiperazine units enabled the convergent total synthesis of five natural pyrroloindole compounds and unnatural congeners. The established chemical method will provide facile access to a broad range of dimerized peptides with the unique scaffold to link two turn structures, which would serve as a powerful tool to create new small- or middle-molecule drug candidates.
Collapse
|
7
|
Mushtaq A, Woodrum D, Thompson S, Adamo D, Lomas D, Favazza C, Lu A, Kwon E. Abstract No. 91 MRI-Guided Cryoablation of Oligo-Metastatic Prostate Cancer to the Pelvic Lymph Nodes. J Vasc Interv Radiol 2023. [DOI: 10.1016/j.jvir.2022.12.138] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023] Open
|
8
|
Fujiki S, Takada T, Nagasawa S, Okada H, Sasano Y, Kwon E, Matsuo Y, Iwabuchi Y. Sequential click modification of a lithium-ion endohedral fullerene connecting small molecules through a dieneazide linker. Chem Commun (Camb) 2023; 59:1237-1240. [PMID: 36632989 DOI: 10.1039/d2cc06301h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A versatile method for the chemical modification of a lithium-ion endohedral fullerene (Li+@C60) to connect various small molecules is described. The designed dieneazide linker enables the facile connection of Li+@C60 with small molecules bearing a terminal alkyne via Huisgen annulation and a subsequent Diels-Alder reaction. This strategy significantly expands the diversity of small molecules to be attached by Li+@C60.
Collapse
|
9
|
Nomura M, Begum Z, Seki C, Okuyama Y, Kwon E, Uwai K, Tokiwa M, Tokiwa S, Takeshita M, Nakano H. Thiourea fused γ-amino alcohol organocatalysts for asymmetric Mannich reaction of β-keto active methylene compounds with imines. RSC Adv 2023; 13:3715-3722. [PMID: 36756606 PMCID: PMC9891089 DOI: 10.1039/d2ra08317e] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 01/18/2023] [Indexed: 01/27/2023] Open
Abstract
Catalytic functionality of new optically active thiourea fused γ-amino alcohols was examined in the asymmetric Mannich reaction of β-keto active methylene compounds with imines to afford chiral Mannich products, β-amino keto compounds, with continuous chiral centers, that are versatile synthetic intermediates for deriving various biologically active compounds. In particular, the thiourea fused γ-amino alcohols showed satisfactory catalytic activity in this reaction and afforded chiral Mannich products in excellent chemical yield (up to 88%) and stereoselectivities (up to syn : anti/93 : 7 dr, up to 99% ee).
Collapse
|
10
|
Begum Z, Seki C, Okuyama Y, Kwon E, Uwai K, Tokiwa M, Tokiwa S, Takeshita M, Nakano H. New boro amino amide organocatalysts for asymmetric cross aldol reaction of ketones with carbonyl compounds. RSC Adv 2023; 13:888-894. [PMID: 36686933 PMCID: PMC9811241 DOI: 10.1039/d2ra06272k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 12/20/2022] [Indexed: 01/05/2023] Open
Abstract
Distinct types of new boron fused primary amino amide organocatalysts were designed and synthesized from commercially available amino acids. Their catalytic activities were investigated in asymmetric crossed aldol reaction of ketones with aromatic aldehydes to afford the corresponding chiral anti-aldol adducts with good chemical yields, moderate diastereoselectivity and good to excellent enantioselectivities (up to 94% yields, up to 90 : 10 dr, up to 94% ee).
Collapse
|
11
|
Yoshizawa R, Inagaki Y, Momma H, Kwon E, Ohara K, Yamaguchi K, Setaka W. Synthesis and fluorescence properties of 9,9-dimethylfluorene-diyl bridged molecular gyrotops: Effects of slight fluorophore motion on fluorescence efficiency in solid state. NEW J CHEM 2023. [DOI: 10.1039/d2nj05873a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The fluorescence of organic molecules has been widely investigated in the development of functional materials. Clarifying the relationship between molecular motion and fluorescence quantum yield (FQY) can aid in developing...
Collapse
|
12
|
Kwon E, Matsukawa T, Hoshikawa A, Ishigaki T, Aoyagi S, Kawachi K, Kasama Y. Direct observation of nucleus of lithium in a C60 fullerene cage by neutron diffraction study. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
13
|
Fu QL, Fujii M, Kwon E. Development of an Internal Calibration Algorithm for Ultrahigh-Resolution Mass Spectra of Dissolved Organic Matter. Anal Chem 2022; 94:10589-10594. [PMID: 35862549 DOI: 10.1021/acs.analchem.2c01342] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In order to obtain a spectrum with high mass accuracy, an internal calibration of Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) is inevitable. This in turn is critical for subsequent data processing and is generally performed using the commercial instrument software DataAnalysis in the benchmark calibration mode. However, no methodological study has systemically addressed the automated internal calibration of FTICR-MS spectra for dissolved organic matter (DOM) from different sources such as terrestrial and aquatic environments. In this study, a new piecewise algorithm, FTMSCalibrate, was developed to automatically calibrate FTICR-MS spectra in both positive and negative ion modes. FTMSCalibrate was found to reproduce 91.7% ± 4.4% (referred to as the true positive ratio) of the chemical formulas obtained by calibration using manual DataAnalysis. In addition to significantly reducing the mass error, FTMSCalibrate is more accurate in terms of the molecular formula assignment for low m/z peaks than Formularity and MFAssignR. FTMSCalibrate was compatible with deprotonated ions for FTICR-MS spectra in the negative ion mode as well as protonated and adduct ions, including Na- and K-adducts, for FTICR-MS spectra in the positive ion mode. These results suggest that FTMSCalibrate publicly available herein is a robust alternative for the internal calibration of FTICR-MS spectra during postdata processing and will facilitate DOM analysis by FTICR-MS.
Collapse
|
14
|
Uchida K, Uematsu I, Iwamoto T, Kwon E, Yoshida S, Kato R, Fukui H. Structural Estimation and Hazard Evaluation of Potentially Explosive Residual Silanes Generated in Semiconductor Manufacturing Processes. Ind Eng Chem Res 2022. [DOI: 10.1021/acs.iecr.1c05007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
15
|
Shigeno M, Hanasaka K, Tohara I, Izumi K, Yamakoshi H, Kwon E, Nozawa-Kumada K, Kondo Y. Direct C-H Carboxylation Forming Polyfunctionalized Aromatic Carboxylic Acids by Combined Brønsted Bases. Org Lett 2022; 24:809-814. [PMID: 35048709 DOI: 10.1021/acs.orglett.1c03866] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
CO2 fixation into electron-deficient aromatic C-H bonds proceeds with the combined Brønsted bases LiO-t-Bu and LiO-t-Am/CsF/18-crown-6 (t-Am = CEtMe2) under a CO2 atmosphere to afford a variety of polyfunctionalized aromatic carboxylic acids.
Collapse
|
16
|
Fu QL, Fujii M, Watanabe A, Kwon E. Formula Assignment Algorithm for Deuterium-Labeled Ultrahigh-Resolution Mass Spectrometry: Implications of the Formation Mechanism of Halogenated Disinfection Byproducts. Anal Chem 2022; 94:1717-1725. [PMID: 35019276 DOI: 10.1021/acs.analchem.1c04298] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Ultrahigh-resolution mass spectrometry (UHR-MS) coupled with isotope labeling has attracted significant attention in elucidating the mechanisms of the transformation of dissolved organic matter (DOM). Herein, we developed a novel formula assignment algorithm based on deuterium (D)-labeled UHR-MS, namely, FTMSDeu, for the first time. This algorithm was employed to determine the precursor molecules of halogenated disinfection byproducts (Xn-DBPs) and to evaluate the relative contribution of electrophilic addition and substitution reactions in Xn-DBP formation according to the H/D exchange of DOM molecules. Further, tandem mass spectrometry with homologous-based network analysis was used to validate the formula assignment accuracy of FTMSDeu in the identification of iodinated disinfection byproducts. Electrophilic substitution accounted for 82-98, 71-89, and 43-45% of the formation for Cl-, Br-, and I-containing Xn-DBPs, respectively, indicating the dominant role of the electrophilic substitution in chlorinated disinfection byproducts with low Br and I concentrations. The absence of putative precursors in some Xn-DBPs also suggests that Xn-DBP formation includes secondary reactions (e.g., oxidation and hydrolysis) in addition to the electrophilic addition and/or substitution of halogens. These findings highlight the significance of isotopically labeled UHR-MS techniques in revealing the transformation of DOM in natural and engineered systems.
Collapse
|
17
|
Nakano H, Ganesan D, Parasuraman P, Begum Z, Seki C, Okuyama Y, Kwon E, Uwai K, Tokiwa M, Tokiwa S, Takeshita M, Thiyagarajan R. New Sugar Based γ-Amino Silyl Ether Organocatalysts for Asymmetric Michael Addition of β-Keto Esters with Nitroolefins. HETEROCYCLES 2022. [DOI: 10.3987/com-21-s(r)2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
18
|
Thiyagarajan R, Begum Z, Seki C, Okuyama Y, Kwon E, Uwai K, Tokiwa M, Tokiwa S, Takeshita M, Nakano H. New small γ-turn type N-primary amino terminal tripeptide organocatalyst for solvent-free asymmetric aldol reaction of various ketones with aldehydes. RSC Adv 2021; 11:38925-38932. [PMID: 35493209 PMCID: PMC9044195 DOI: 10.1039/d1ra08635a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 11/30/2021] [Indexed: 01/18/2023] Open
Abstract
New small γ-turn type N-primary amino terminal tripeptides were synthesized and their functionality as an organocatalyst was examined in the asymmetric aldol reaction of various ketones with different aromatic aldehydes under solvent-free neat conditions to afford the desired chiral anti-aldol products in good to excellent chemical yields, diastereoselectivities and enantioselectivities (up to 99%, up to syn : anti/13 : 87 dr, up to 99% ee).
Collapse
|
19
|
Koshino S, Taniguchi T, Monde K, Kwon E, Hayashi Y. Enantiodivergent One-Pot Synthesis of Axially Chiral Biaryls Using Organocatalyst-Mediated Enantioselective Domino Reaction and Central-to-Axial Chirality Conversion. Chemistry 2021; 27:15786-15794. [PMID: 34524720 DOI: 10.1002/chem.202102797] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Indexed: 01/03/2023]
Abstract
Enantiodivergent one-pot synthesis of biaryls was developed using a catalytic amount of a single chiral source. A domino organocatalyst-mediated enantioselective Michael reaction and aldol condensation provided centrally chiral dihydronaphthalenes with excellent enantioselectivity, from which an enantiodivergent chirality conversion from central-to-axial chirality was achieved. Both enantiomers of biaryls were obtained with excellent enantioselectivity. All transformations can be conducted in a single reaction vessel. A plausible reaction mechanism for the enantiodivergence is proposed.
Collapse
|
20
|
Jang H, Choi Y, Kwon E, Choi N, Jang Y, Song J, Shin S. Optimal application of compressive palatal stents following mesiodens removal in pediatric patients: A Randomized Controlled Trial. Med Oral Patol Oral Cir Bucal 2021; 26:e808-e814. [PMID: 34704974 PMCID: PMC8601646 DOI: 10.4317/medoral.24802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 10/04/2021] [Indexed: 11/17/2022] Open
Abstract
Background There is no scientific evidence supporting the choice of a palatal stent in patients who underwent removal of an impacted supernumerary tooth. We aimed to investigate the effects of palatal stents in patients who underwent supernumerary tooth removal through a palatal approach and to suggest the optimal stent thickness and material. Material and Methods We recruited 144 patients who underwent extraction of a supernumerary tooth between the maxillary anterior teeth. Subjects were assigned to a control group (CG) or one of four compressive palatal stent groups (CPSGs) classified by the thickness and material of the thermoplastic acrylic stent used. Palatal gingival swelling and objective indices (healing, oral hygiene, gingival, and plaque) were evaluated before surgery and on postoperative days (PODs) 3, 7, and 14; pain/discomfort and the Child Oral Health Impact Profile (COHIP) were assessed as subjective indices of the effects of the stent. Results The CPSGs showed faster healing than did the CG on PODs 7 (P<0.001) and 14 (P=0.043); swelling was measured by 1.64±0.88 mm and 4.52±0.39 mm, respectively. Although swelling was least in the 4-mm hard group (0.92±0.33 mm), the difference compared with that in the 2-mm hard group (1.01±0.18 mm) was not significant (P=0.077). The CPSGs showed better COHIP (P<0.001-0.036) and pain scores (P<0.001) than did the CG on PODs 1-3. Conclusions Compressive palatal stents reduce discomfort by decreasing pain and alleviating swelling. Although a stent is effective regardless of its thickness and material, 2-mm hard stents maximized such positive effects with minimal discomfort. Key words:Supernumerary tooth, tooth Extraction, postoperative care, oral Health, pediatric dentistry.
Collapse
|
21
|
Toyota K, Mikami S, Matsuo A, Kwon E. Synthesis of 4,7′-Bibenzo[b]thiophenes Bearing Several Different Substituents at 2-, 2′-, 4′-, and 7-Positions; Structurally Featured Molecular Scaffolds for Selective Substitution. Synlett 2021. [DOI: 10.1055/s-0040-1719839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
AbstractFour isomers of 4,7′-bibenzothiophene scaffolds bearing two different halogen (Br, Cl) and triisopropylsilyl substituents have been synthesized from the two multihalobenzo[b]thiophenes via iodoselective Miyaura borylation reaction using potassium benzoate as a base. Further investigation into the reactivity of 4,7′-bibenzothiophenes in substitution reaction, Suzuki–Miyaura cross-coupling reaction, and C–H direct arylation reaction revealed that tetrasubstituted 4,7′-bibenzothiophenes can be synthesized site- (chemo-) selectively, which are promising novel components for molecular architecture.
Collapse
|
22
|
Li J, Kwon E, Lear MJ, Hayashi Y. Halogen Bonding of
N
‐Halosuccinimides with Amines and Effects of
Brønsted
Acids in Quinuclidine‐Catalyzed Halocyclizations. Helv Chim Acta 2021. [DOI: 10.1002/hlca.202100080] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
23
|
Tu Y, Inagaki Y, Kwon E, Setaka W. Template Synthesis for Disilamacrocycles via Ring-closing Metathesis. CHEM LETT 2021. [DOI: 10.1246/cl.210234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
24
|
Parasuraman P, Ganesan D, Begum Z, Seki C, Okuyama Y, Kwon E, Uwai K, Tokiwa M, Tokiwa S, Takeshita M, Nakano H. Simple amino silyl ether organocatalyst for asymmetric hetero Diels-Alder reaction of isatins with enones. Chirality 2021; 33:454-464. [PMID: 33987900 DOI: 10.1002/chir.23319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/19/2021] [Accepted: 04/28/2021] [Indexed: 11/08/2022]
Abstract
New two catalysts component system comprising of a primary β-amino silyl ethers as an organocatalyst and N-protected amino acids as a co-catalyst put together worked as an efficient organocatalyst system in the hetero Diels-Alder reaction of isatins with enones affording the chiral spirooxindole-tetrahydropyranones in good chemical yields and stereoselectivities (up to 94%, up to dr 78:22., up to 85% ee).
Collapse
|
25
|
Ishibashi O, Nishiyama M, Kwon E, Hashimoto M, Kuwahara S, Enomoto M. Semipinacol rearrangement of a bicyclo[7.2.0]undecane framework into a bicyclo[6.3.0]undecane skeleton: a model study on the biosynthesis of seiridiasteriscane A. Biosci Biotechnol Biochem 2021; 85:1621-1627. [PMID: 33960363 DOI: 10.1093/bbb/zbab083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 05/04/2021] [Indexed: 11/15/2022]
Abstract
Seiridiasteriscane A is an asteriscane-type sesquiterpenoid bearing a trans-fused bicyclo[6.3.0]undecane skeleton. Although its biosynthesis has been proposed to involve a semipinacol rearrangement of a putative intermediary acetate bearing a bicyclo[7.2.0]undecane ring system (presumably derived from coisolated pestalotiopsin M) followed by epimerization of the resulting cis-fused seiridiasteriscane B, such a type of semipinacol rearrangement has never been reported so far. Our model study revealed that a 1-hydroxybicyclo[7.2.0]undecan-2-yl acetate underwent a smooth and stereospecific semipinacol rearrangement with the assistance of Et2AlCl to give the corresponding bicyclo[6.3.0]undecane-9-one. In addition, the resulting cis-fused 5,8-bicyclic ketone was partially epimerized to the corresponding trans-fused ketone by prolonged adsorption onto a silica gel plate. These results may support a recently proposed biosynthetic pathway of seiridiasteriscane A.
Collapse
|