- Biogenesis-Guided Synthesis and Structural Revision of Sarocladione Enabled by Ruthenium-Catalyzed Endoperoxide Fragmentation
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Sarocladione is the first 5,10:8,9-diseco-steroid with a 14-membered macrocyclic diketone framework to have been isolated from a natural source. Herein we report a biomimetic synthesis of sarocladione in only two or seven steps from inexpensive, commercially available ergosterol. The key feature of this synthesis was a novel ruthenium-catalyzed endoperoxide fragmentation, which transformed various saturated endoperoxides into olefinic diketones by cleavage of two C?C bonds. This synthesis allowed us to unambiguously determine the structure of sarocladione and provided experimental support for its revised biosynthetic origin. This work also vividly demonstrates that consideration of the biogenesis is a powerful tool for elucidating the structures of natural products.
- Ning, Yuhan,Tian, Hailong,Gui, Jinghan
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supporting information
p. 11222 - 11226
(2021/04/19)
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- Enantiopure 2,9-Dideuterodecane – Preparation and Proof of Enantiopurity
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(R,R)- and (S,S)-(2,9-2H2)-n-Decane were prepared regio- and stereospecifically in 25–26 % yield over five steps from commercially available enantiopure (R)- and (S)-propylene oxide, respectively. The synthetic procedure involved nucleophilic displacement of (R)- and (S)-4-toluenesulfonic acid 1-methyl-4-pentenyl ester with LiAlD4 to furnish the respective (5-2H)-1-hexenes. Subsequent olefin metathesis and reduction of the double bond furnished the title compounds. The optical purity of (R,R)- and (S,S)-(2,9-2H2)-n-decane could not be determined by chromatography or polarimetry. Therefore, (R,R)- and (R,S)-(5-2H)-3-hydroxy-2-hexanone were prepared from their respective hexenes by Wacker oxidation, followed by enantioselective α-hydroxylation. The enantiopurity could then be determined by NMR spectroscopy because the stereospecifically deuterated hydroxyketones showed separated signals for the subterminal carbon atom (C-5) in the 13C NMR spectrum.
- Christoffers, Jens,Eru?ar, Gülsera,Fsadni, Miriam H.,Golding, Bernard T.,Mitschke, Nico,Roberts, Amy R.,Sadeghi, Majid M.,Wilkes, Heinz
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p. 3854 - 3863
(2021/08/24)
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- Light-Stabilized Dynamic Materials
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The light-responsive adaptation of polymer materials typically requires different wavelengths or additional heat to induce reversible covalent bond formation and dissociation. Here, we bypass the use of invasive triggers by introducing light-stabilized dynamic materials that can undergo a repeatable change in topology from a covalently cross-linked material into a liquid polymer formulation by switching one visible light source on-and-off without the need for any additional triggers. Specifically, we exploit the photo-Diels-Alder reaction of triazolinediones with naphthalenes as a dynamic covalent cross-linking platform that enables green light-induced network formation, while the cross-linked material collapses through spontaneous cycloreversion upon standing in the dark at ambient temperature. Importantly, the covalent cross-links remain stabilized for as long as visible light is present, thereby retaining the material's structural integrity. This enables their potential use in an array of light-directed applications whereby network properties such as stiffness can be tuned by the mildest trigger of all: darkness.
- Houck, Hannes A.,Blasco, Eva,Du Prez, Filip E.,Barner-Kowollik, Christopher
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supporting information
p. 12329 - 12337
(2019/08/27)
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- Improved and scalable synthesis of building blocks for the modular synthesis of teraryl-based alpha-helix mimetics
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The modular synthesis of teraryl-based alpha-helix mimetics can be accomplished by sequential Suzuki-couplings of arylboronic acid building blocks with 4-iodophenyltriflate core-fragments. We report about new synthetic accesses to core fragments featuring
- Trobe, Melanie,Breinbauer, Rolf
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p. 509 - 521
(2016/03/19)
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- Cinnamic acid derivatives as inhibitors for chorismatases and isochorismatases
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Chorismatases and isochorismatases catalyse the hydrolysis of chorismate or isochorismate leading to unsaturated cyclohexenoic acid derivatives. Based on simplification of the physiological substrates, two cinnamic acid-derived compounds, differing in the
- Hubrich, Florian,Mordhorst, Silja,Andexer, Jennifer N.
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supporting information
p. 1477 - 1481
(2013/03/14)
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- Convergent synthesis of deoxypropionates
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Metallacycle-mediated allylic alcohol-alkyne reductive cross-coupling is described as a convergent solution to the synthesis of deoxypropionates. This approach offers superior step-economy in comparison to available strategies based on multistep iterative chain elongation. The technique is demonstrated in a concise synthesis of the C1-C11 subunit of borrelidin, and a total synthesis of (-)-vittatalactone. Copyright
- Diez, Peter S.,Micalizio, Glenn C.
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supporting information; experimental part
p. 5152 - 5156
(2012/07/27)
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- Stereoselective synthesis of a monocyclic peloruside A analogue
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Chemical Equation Presentation The stereoselective synthesis of the monocyclic peloruside A analogue 4 has been achieved, following a new efficient approach for the introduction of the side chain, involving a late-stage addition of vinyl lithium species 7a to aldehyde 8. Further key steps are a highly diastereoselective allyltitanation reaction and a RCM-based macrocyclization.
- Wulischleger, Christoph W.,Gertsch, Juerg,Altmann, Karl-Heinz
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supporting information; experimental part
p. 1120 - 1123
(2010/06/13)
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- Extreme rate acceleration by axial thiolate coordination on the isomerization of endoperoxide catalyzed by iron porphyrin
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(Chemical Equation Presented) A coordinated effort: The isomerization mechanism of prostaglandin H2 (PGH2), which is catalytically isomerized to prostacyclin or thromboxane A2 by cytochrome P450s, was investigated using a hemethiolate complex and an endoperoxide. Isomerization of endoperoxides proceeded very rapidly with this complex, whereas imidazole- or chloride-ligated heme had slight or no catalytic activity (see scheme).
- Yamane, Takehiro,Makino, Kohei,Umezawa, Naoki,Kato, Nobuki,Higuchi, Tsunehiko
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supporting information; experimental part
p. 6438 - 6440
(2009/03/11)
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- Dirhodium(II) tetra(N-(dodecylbenzenesulfonyl)prolinate) catalyzed enantioselective cyclopropenation of alkynes
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Dirhodium tetrakis((S)-N-(dodecylbenzenesulfonyl)prolinate) (Rh 2(S-DOSP)4) is an effective chiral catalyst for the enantioselective cyclopropenation of alkynes by methyl aryldiazoacetates.
- Davies, Huw M. L.,Lee, Gene H.
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p. 1233 - 1236
(2007/10/03)
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