- SYNTHESIS AND DETERMINATION OF THE ABSOLUTE CONFIGURATION OF THE MACROLIDE (+)-CONGLOBATIN
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(+)-Conglobatin is synthesized from (-)-(2S,4R)-2,4-dimethyl glutaric acid halfester in 15 steps (total yield 4.4percent).The synthesis proves the sense of chirality of the natural (-)-conglobatin to be opposite to the one previously assigned.
- Schregenberger, Christian,Seebach, Dieter
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- From dicarbonylallene to 1-aryl-3,6-dimethyl-4-aminoaryl-2-pyridones: a one-pot versatile and uncatalyzed synthesis
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Reaction of amines with an allenic precursor leads to new 1-aryl-3,6-dimethyl-4-aminoaryl-2-pyridones in good yields. These syntheses can be performed in two distinct steps, allowing the possibility to introduce different substituents in the positions 1 a
- Boisse, Thomas,Rigo, Beno?t,Millet, Régis,Hénichart, Jean-Pierre
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- 7-Step total synthesis of (+)-EBC-329: Photoisomerisation reveals new: Seco -casbane family member
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The first seco-casbane, EBC-329, isolated from the Australian rainforest, was synthesised from (+)-2-carene in seven steps. This endeavour not only established the absolute stereochemical assignment as (8R,9S)-EBC-329, but also identified, via photoisomer
- Vanden Berg, Timothy J.,Pinkerton, David M.,Williams, Craig M.
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- Organocatalytic epoxidation and allylic oxidation of alkenes by molecular oxygen
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Pyrrole-proline diketopiperazine (DKP) acts as an efficient mediator for the reduction of dioxygen by Hantzsch ester under mild conditions to allow the aerobic metal-free epoxidation of electron-rich alkenes. Mechanistic crossovers are underlined, explaining the dual role of Hantzsch ester as a reductant/promoter of the DKP catalyst and a simultaneous competitor for the epoxidation of alkenes when HFIP is used as a solvent. Expansion of this protocol to the synthesis of allylic alcohols was achieved by adding a catalytic amount of selenium dioxide as an additive, revealing a superior method to the classical application of t-BuOOH as a selenium dioxide oxidant.
- Orfanidou, Maria,Petsi, Marina,Zografos, Alexandros L.
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supporting information
p. 9172 - 9178
(2021/11/30)
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- Ring-closing metathesis approaches towards the total synthesis of rhizoxins
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Efforts are described towards the total synthesis of the bacterial macrolide rhizoxin F, which is a potent tubulin assembly and cancer cell growth inhibitor. A significant amount of work was expanded on the construction of the rhizoxin core macrocycle by ring-closing olefin metathesis (RCM) between C(9) and C(10), either directly or by using relay substrates, but in no case was ringclosure achieved. Macrocycle formation was possible by ring-closing alkyne metathesis (RCAM) at the C(9)/C(10) site. The requisite diyne was obtained from advanced intermediates that had been prepared as part of the synthesis of the RCM substrates. While the direct conversion of the triple bond formed in the ring-closing step into the C(9)-C(10) E double bond of the rhizoxin macrocycle proved to be elusive, the corresponding Z isomer was accessible with high selectivity by reductive decomplexation of the biscobalt hexacarbonyl complex of the triple bond with ethylpiperidinium hypophosphite. Radical-induced double bond isomerization, full elaboration of the C(15) side chain, and directed epoxidation of the C(11)-C(12) double bond completed the total synthesis of rhizoxin F.
- Altmann, Karl-Heinz,Liniger, Marc,Neuhaus, Christian M.
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supporting information
(2020/10/18)
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- Metal-Free Transfer Hydroiodination of C-C Multiple Bonds
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The design and a gram-scale synthesis of a bench-stable cyclohexa-1,4-diene-based surrogate of gaseous hydrogen iodide are described. By initiation with a moderately strong Br?nsted acid, hydrogen iodide is transferred from the surrogate onto C-C multiple bonds such as alkynes and allenes without the involvement of free hydrogen iodide. The surrogate fragments into toluene and ethylene, easy-to-remove volatile waste. This hydroiodination reaction avoids precarious handling of hydrogen iodide or hydroiodic acid. By this, a broad range of previously unknown or difficult-to-prepare vinyl iodides can be accessed in stereocontrolled fashion.
- Chen, Weiqiang,Walker, Johannes C. L.,Oestreich, Martin
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p. 1135 - 1140
(2019/01/11)
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- NOVEL LACTAM DERIVATIVES HAVING THERAPEUTIC EFFECT ON CANCERS
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The present invention relates to a novel lactam derivative having a cancer therapeutic effect or a pharmaceutically acceptable salt thereof and a pharmaceutical composition containing the same as an active ingredient. The novel lactam derivative in accordance with the present invention is capable of selectively and effectively inhibiting the growth of cancer cells, that is B-cell non-Hodgkinandprime;s lymphoma, thereby being usefully used as a pharmaceutical composition for treating cancer or inhibiting the growth of cancer cells.COPYRIGHT KIPO 2015
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Paragraph 0033-0034; 0053-0055
(2016/11/14)
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- A multicomponent Ni-, Zr-, and Cu-catalyzed strategy for enantioselective synthesis of alkenyl-substituted quaternary carbons
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The availability of enantiomerically enriched carbonyl-containing compounds is essential to the synthesis of biologically active molecules. Since catalytic enantioselective conjugate addition (ECA) reactions directly generate the latter valuable class of molecules, the design and development of such protocols represents a compelling objective in modern chemistry. Herein, we disclose the first solution to the problem of ECA of alkenyl groups to acyclic trisubstituted enones, an advance achieved by adopting an easily modifiable and fully catalytic approach. The requisite alkenylaluminum reagents are synthesized with exceptional site- and/or stereoselectivity by a Ni-catalyzed hydroalumination process, and the necessary enones are prepared through a site- and stereoselective zirconocene-catalyzed carboalumination/acylation reaction. The all-catalytic procedure is complete within four hours, furnishing the desired products in up to 77 % overall yield and 99:1 enantiomeric ratio. One-two-three punch: Ni-catalyzed alkyne hydroalumination, Zr-catalyzed alkyne carbometalation/acylation, and Cu-catalyzed enantioselective conjugate addition are combined for accessing acyclic organic molecules that contain an alkene-substituted quaternary carbon stereogenic center. The entire process takes less than four hours and affords products in up to 77 % overall yield and 99:1 enantiomeric ratio. Copyright
- McGrath, Kevin P.,Hoveyda, Amir H.
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supporting information
p. 1910 - 1914
(2014/03/21)
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- Convergent asymmetric synthesis of (+)-aureothin employing an oxygenase-mediated resolution step
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Need an enzymatic push? The desymmetrization of α,α'-dimethoxy- γ-pyrone allows the convergent and rapid preparation of the complete carbon skeleton of (+)-aureothin (see scheme). The final step in the synthesis of the target molecule is the regiodivergen
- Henrot, Matthias,Richter, Martin E.A.,Maddaluno, Jacques,Hertweck, Christian,De Paolis, Micha?l
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p. 9587 - 9591
(2012/10/30)
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- A bismuth(III)-catalyzed friedel-crafts cyclization and stereocontrolled organocatalytic approach to (-)-platensimycin
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A high yielding route to the (-)-platensimycin core is communicated. This entailed the discovery of Bi(OTf)3 to catalyze a Friedel-Crafts cyclization of a free lactol, supplemented by LiClO4 to suppress the Lewis basicity of the sulfonate group. After TBAF-promoted cyclodearomatization, a diastereoselective conjugate reduction of a dienone was achieved by adopting amine-based organocatalytic rationales to reverse the inherent steric control of the substrate.
- Eey, Stanley T.-C.,Lear, Martin J.
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p. 5510 - 5513
(2011/03/18)
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- Specific isotope enrichment of methyl methacrylate
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A synthetic scheme has been developed to prepare methyl methacrylate specifically 13C-labelled at all different positions and in any combination of positions, from simple, commercially available starting materials. According to this scheme methyl (1-13C) and methyl (2-13C)methacrylate (1a and 1b) have been prepared with high label incorporation (99%).
- Werkhoven, Thekla M.,Van Nispen, Reinier,Lugtenburg, Johan
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p. 2909 - 2914
(2007/10/03)
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- A general route to "carba" peptide bond replacements: Unequivocal synthesis of Boc-L-Phe-ψ(CH2-CH2)-L-Ala-OH and Boc-L-Phe-ψ(CH2-CH2)-D-Ala-OH
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An unambiguous synthesis of Boc-L-Phe-ψ(CH2-CH2)-L-Ala-OH and BocL-Pheψ(CH2-CH2)-D-AlaOH from Boc-L-phenylalanine, through lactame intermediates (3R,6R)-3-m
- Rodriguez, Marc,Aumelas, Andre,Martinez, Jean
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p. 5153 - 5156
(2007/10/02)
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