- Structure revision of medermycin/lactoquinomycin a and of related C-8 glycosylated naphthoquinones.
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[reaction: see text] On the basis of chemical and spectral data, the structure of the medermycin/lactoquinomycin A has been revised, which has also led to the revision of related C-glycosylated naphthoquinone antibiotics such as lactoquinomycin B, menoxymycins A and B, G15-F, and G15-G.
- Leo, Pierre-Marc,Morin, Christophe,Philouze, Christian
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- Sustainable Passerini-tetrazole three component reaction (PT-3CR): selective synthesis of oxaborol-tetrazoles
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A sustainable catalyst- and solvent-free Passerini-tetrazole three component reaction (PT-3CR) has been developed for the selective synthesis of benzoxaborol-tetrazoles for the first time. The synthetic potential of oxaboroles was demonstrated towards various functionalized tetrazoles, which are otherwise difficult to achieve through conventional PT-3CR from aromatic aldehydes/ketones. The reaction features high practicality, broad substrate scope and excellent yields (80-98%). Preliminary results of the asymmetric PT-3CR are also shown for the synthesis of chiral benzoxaboroles.
- Singh, Akansha,Kumar, Ravindra
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supporting information
p. 9708 - 9711
(2021/09/30)
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- Catalytic Synthesis of 1 H-2-Benzoxocins: Cobalt(III)-Carbene Radical Approach to 8-Membered Heterocyclic Enol Ethers
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The metallo-radical activation of ortho-allylcarbonyl-aryl N-arylsulfonylhydrazones with the paramagnetic cobalt(II) porphyrin catalyst [CoII(TPP)] (TPP = tetraphenylporphyrin) provides an efficient and powerful method for the synthesis of novel 8-membered heterocyclic enol ethers. The synthetic protocol is versatile and practical and enables the synthesis of a wide range of unique 1H-2-benzoxocins in high yields. The catalytic cyclization reactions proceed with excellent chemoselectivities, have a high functional group tolerance, and provide several opportunities for the synthesis of new bioactive compounds. The reactions are shown to proceed via cobalt(III)-carbene radical intermediates, which are involved in intramolecular hydrogen transfer (HAT) from the allylic position to the carbene radical, followed by a near-barrierless radical rebound step in the coordination sphere of cobalt. The proposed mechanism is supported by experimental observations, density functional theory (DFT) calculations, and spin trapping experiments.
- De Bruin, Bas,De Zwart, Felix J.,Li, Zirui,Mathew, Simon,Wolzak, Lukas A.,Zhou, Minghui
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supporting information
p. 20501 - 20512
(2021/12/03)
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- Catalytic synthesis of isoquinolines via intramolecular migration of n-aryl sulfonyl groups on 1,5-yne-imines
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Isoquinolines are ubiquitous structural motifs in a variety of bioactive compounds, including medicinal agents and natural products. The development of novel strategies for the preparation of isoquinolines using non-toxic organocatalysts is thus worthwhile. Herein, we report a simple amine-catalyzed protocol for the synthesis of isoquinolines from 1,5-yne-imines via the intramoleular migration of an N-aryl sulfonyl group to the carbon atom of the alkyne moiety.
- Hoshimoto, Yoichi,Kumar, Ravindra,Nishimura, Chika,Ogoshi, Sensuke,Sasaoka, Yukari
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supporting information
p. 182 - 186
(2020/04/27)
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- Heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis
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A general and efficient method for heterocyclization involving benzylic C(sp3)-H functionalization enabled by visible light photoredox catalysis to access a wide range of structurally diverse oxygen as well as nitrogen heterocycles up to a gram scale is reported. The potential application of this new methodology is demonstrated by the total synthesis of (-)-codonopsinine and (+)-centrolobine. Herein it is proposed that selectfluor, unlike a fluorinating reagent, acts as an oxidative quencher and a hydrogen radical acceptor.
- Pandey, Ganesh,Laha, Ramkrishna,Mondal, Pradip Kumar
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supporting information
p. 9689 - 9692
(2019/08/15)
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- Highly efficient activation of organosilanes with η2-aldehyde nickel complexes: Key for catalytic syntheses of aryl-, vinyl-, and alkynyl-benzoxasiloles
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An η2-aldehyde nickel complex was utilized as an effective activator for an organosilane in order to generate a hypervalent silicate reactant for the first time. This method was successfully applied to the highly efficient syntheses of 3-aryl-, vinyl-, and alkynyl-2,1-benzoxasiloles from benzaldehydes with aryl-, vinyl-, and alkynylsilyl groups at the ortho position. Initial mechanistic studies revealed that an intermolecular aryl transfer process was involved in the reaction mechanism. The formation of an η2-aldehyde complex was directly confirmed by NMR.
- Hoshimoto, Yoichi,Yabuki, Hayato,Kumar, Ravindra,Suzuki, Haruka,Ohashi, Masato,Ogoshi, Sensuke
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supporting information
p. 16752 - 16755
(2015/01/16)
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- Synthesis of five- and six-membered benzocyclic ketones through intramolecular alkene hydroacylation catalyzed by Nickel(0)/N-Heterocyclic Carbenes
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Getting some closure: Mechanistic studies supported the participation of an oxanickelacycle complex in the hydroacylation step of the title reaction, which proceeds without decarbonylation even in the absence of well-known chelation assistance by heteroatoms. Copyright
- Hoshimoto, Yoichi,Hayashi, Yukari,Suzuki, Haruka,Ohashi, Masato,Ogoshi, Sensuke
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supporting information
p. 10812 - 10815
(2013/01/15)
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- DIAMINOPROPANE DERIVED MACROCYCLES AS INHIBITORS OF BETA AMYLOID PRODUCTION
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There is provided a series of macrocyclic diaminopropanes of Formula (I) or a stereoisomer; or a pharmaceutically acceptable salt thereof, wherein R1, R2, R3, m, n, W, X, Y, Z and L as defined herein, their pharmaceutical compositions and methods of use. These novel compounds inhibit the processing of amyloid precursor protein (APP) by β-secretase and, more specifically, inhibit the production of Aβ-peptide. The present disclosure is directed to compounds useful in the treatment of neurological disorders related to β-amyloid production, such as Alzheimer's disease and other conditions affected by anti-amyloid activity.
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Page/Page column 30
(2008/12/07)
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- BORON-CONTAINING SMALL MOLECULES AS ANTI-INFLAMMATORY AGENTS
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Methods of treating anti-inflammatory conditions through the use of boron-containing small molecules are disclosed.
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Page/Page column 40
(2008/06/13)
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- INTRAMOLECULAR CYCLOADDITIONS WITH ISOBENZOFURANS I
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Intramolecular Diels-Alder reactions with isobenzofurans (5,12) offer an attractive route for the preparation of polycyclic systems (6,13).
- Friedrichsen, Willy,Koenig, B. Michael,Hildebandt, Knut,Debaerdemaeker, Tony
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p. 297 - 302
(2007/10/02)
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