- Scalable Biomimetic Syntheses of Paeciloketal B, 1- epi-Paeciloketal B, and Bysspectin A
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The first total synthesis of the benzannulated 5,5-spiroketal natural products paeciloketal B and 1-epi-paeciloketal B has been achieved in 10 linear steps employing a biomimetic spiroketalization. This approach also furnished the related natural product
- Brimble, Margaret A.,Davison, Emma K.,Shepperson, Caitlin E.,Wilson, Zoe E.
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supporting information
p. 2345 - 2351
(2021/08/30)
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- Stereoselective Oxidative Cyclization ofN-Allyl Benzamides to Oxaz(ol)ines
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This study presents an enantioselective oxidative cyclization ofN-allyl carboxamides via a chiral triazole-substituted iodoarene catalyst. The method allows the synthesis of highly enantioenriched oxazolines and oxazines, with yields of up to 94% and enantioselectivities of up to 98% ee. Quaternary stereocenters can be constructed and, besidesN-allyl amides, the corresponding thioamides and imideamides are well tolerated as substrates, giving rise to a plethora of chiral 5-memberedN-heterocycles. By applying a multitude of further functionalizations, we finally demonstrate the high value of the observed chiral heterocycles as strategic intermediates for the synthesis of other enantioenriched target structures.
- Abazid, Ayham H.,Hollwedel, Tom-Niklas,Nachtsheim, Boris J.
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supporting information
p. 5076 - 5080
(2021/07/19)
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- Evolution of N-Heterocycle-Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)-Mediated Oxidative Transformations
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The reactivity of ortho-functionalized N-heterocycle-substituted iodoarenes (NHIAs) as organocatalysts in iodine(I/III)-mediated oxidations was systematically investigated in the α-tosyloxylation of ketones as the model reaction. During a systematic catalyst evolution, it was found that NH-triazoles and benzoxazoles have the most significant positive influence on the reactivity of the central iodine atom. A further catalyst improvement which focused on the substitution pattern of the arene revealed a remarkable ortho-effect. By introduction of an o-OMe group we were able to generate a novel NHIA with a so far unseen catalytic efficiency. This new catalyst is not only easy to synthesize but also enabled the α-tosyloxylation of carbonyl compounds at the lowest reported catalyst loading of only 1 mol%. Finally, the performance of this iodine(I) catalyst was successfully demonstrated in intramolecular oxidative couplings of biphenyls and oxidative rearrangements. (Figure presented.).
- Boelke, Andreas,Nachtsheim, Boris J.
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p. 184 - 191
(2019/12/11)
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- Synthesis of Functionalized Alkylidene Indanes and Indanones through Tandem Phosphine-Palladium Catalysis
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Densely functionalized alkylidene indanes and indanones can be prepared efficiently in one pot, in high yields with good stereoselectivities (in some cases exclusively the Z-isomer), through a route involving phosphine-catalyzed Michael addition followed
- Fan, Yi Chiao,Kwon, Ohyun
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supporting information
p. 2058 - 2061
(2015/05/20)
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- A practical in situ generation of the schwartz reagent. reduction of tertiary amides to aldehydes and hydrozirconation
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A new, highly efficient in situ protocol (Cp2ZrCl2/LiAlH(OBu-t)3) is described for the generation of the Schwartz reagent which provides a convenient method for the amide to aldehyde reduction and the regioselective hydrozirconation-iodination of alkynes and alkenes. Highlighted are chemoselective reductions of benzamides derived by directed ortho metalation (DoM) chemistry, allowing the synthesis of valuable 1,2,3-substituted benzaldehydes. The single-step, three-component process proceeds in a very short reaction time, shows excellent functional group compatibility, and uses inexpensive and long-storage stable reducing reagents.
- Zhao, Yigang,Snieckus, Victor
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supporting information
p. 390 - 393
(2014/04/03)
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- Enantioselective synthesis of multisubstituted biaryl skeleton by chiral phosphoric acid catalyzed desymmetrization/kinetic resolution sequence
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Described herein is the enantioselective synthesis of multisubstituted biaryl derivatives by chiral phosphoric acid catalyzed asymmetric bromination. Two asymmetric reactions (desymmetrization and kinetic resolution) proceeded successively to afford chiral biaryls in excellent enantioselectivities (up to 99% ee). Both experimental and computational studies suggested that this excellent selectivity could be achieved via a highly organized hydrogen bond network among a substrate, a catalyst (chiral phosphoric acid), and a brominating reagent (N-bromophthalimide).
- Mori, Keiji,Ichikawa, Yuki,Kobayashi, Manato,Shibata, Yukihiro,Yamanaka, Masahiro,Akiyama, Takahiko
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p. 3964 - 3970
(2013/04/24)
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- Design and synthesis of simplified taxol analogs based on the T-Taxol bioactive conformation
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A series of compounds designed to adopt a conformation similar to the tubulin-binding T-Taxol conformation of the anticancer drug paclitaxel has been synthesized. Both the internally bridged analogs 37-39, 41 and the open-chain analogs 27-29 and 43 were prepared. The bridged analogs 37-39 and 41 were synthesized by Grubbs' metatheses of compounds 30-32 and 33, which, in turn, were prepared by coupling β-lactams 24-26 with alcohols 22 and 23. Both the bridged and the open-chain analogs showed moderate to good cytotoxicity.
- Zhao, Jielu,Bane, Susan,Snyder, James P.,Hu, Haipeng,Mukherjee, Kamalika,Slebodnick, Carla,Kingston, David G.I.
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experimental part
p. 7664 - 7678
(2012/01/05)
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- Synthesis of methoxy substituted centrally chiral triynes as precursors of functionalised nonracemic helicene-like compounds
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A modular synthesis of a series of methoxy substituted optically pure aromatic triynes (-)-(S)-5-9 and (-)-(R)-10 is presented. It relies on key operations such as substitution of benzylic bromine with an alkoxy group and aryl-alkyne coupling reaction to
- Krausova, Zuzana,Sehnal, Petr,Teply, Filip,Stara, Irena G.,Stary, Ivo,Saman, David,Cvacka, Josef,Fidler, Pavel
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p. 1499 - 1522
(2008/09/16)
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- Towards a total synthesis of the new anticancer agent mensacarcin: Synthesis of the carbocyclic core
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A synthesis of the carbocyclic core associated with the new anti-cancer agent mensacarcin (1) is reported. The strategy involves the synthesis of several novel highly substituted aromatic compounds, such as 12 and 23. The lithium derivative of 12 readily
- Tietze, Lutz F.,Stewart, Scott G.,Polomska, Marta E.,Modi, Andrea,Zeeck, Axel
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p. 5233 - 5242
(2007/10/03)
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