- The Silicon-Hydrogen Exchange Reaction: A Catalytic σ-Bond Metathesis Approach to the Enantioselective Synthesis of Enol Silanes
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The use of chiral enol silanes in fundamental transformations such as Mukaiyama aldol, Michael, and Mannich reactions as well as Saegusa-Ito dehydrogenations has enabled the chemical synthesis of enantiopure natural products and valuable pharmaceuticals. However, accessing these intermediates in high enantiopurity has generally required the use of either stoichiometric chiral precursors or stoichiometric chiral reagents. We now describe a catalytic approach in which strongly acidic and confined imidodiphosphorimidates (IDPi) catalyze highly enantioselective interconversions of ketones and enol silanes. These "silicon-hydrogen exchange reactions"enable access to enantiopure enol silanes via tautomerizing σ-bond metatheses, either in a deprotosilylative desymmetrization of ketones with allyl silanes as the silicon source or in a protodesilylative kinetic resolution of racemic enol silanes with a carboxylic acid as the silyl acceptor.
- Zhou, Hui,Bae, Han Yong,Leutzsch, Markus,Kennemur, Jennifer L.,Bécart, Diane,List, Benjamin
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supporting information
p. 13695 - 13700
(2020/08/24)
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- Enantioselective Synthesis of Chiral Oxime Ethers: Desymmetrization and Dynamic Kinetic Resolution of Substituted Cyclohexanones
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Axially chiral cyclohexylidene oxime ethers exhibit unique chirality because of the restricted rotation of C=N. The first catalytic enantioselective synthesis of novel axially chiral cyclohexylidene oximes has been developed by catalytic desymmetrization of 4-substituted cyclohexanones with O-arylhydroxylamines and is catalyzed by a chiral BINOL-derived strontium phosphate with excellent yields and good enantioselectivities. In addition, chiral BINOL-derived phosphoric acid catalyzed dynamic kinetic resolution of α-substituted cyclohexanones has been performed and yields versatile intermediates in high yields and enantioselectivities.
- Nimmagadda, Sri Krishna,Mallojjala, Sharath Chandra,Woztas, Lukasz,Wheeler, Steven E.,Antilla, Jon C.
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supporting information
p. 2454 - 2458
(2017/02/23)
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- A Versatile Route to Unstable Diazo Compounds via Oxadiazolines and their Use in Aryl–Alkyl Cross-Coupling Reactions
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Coupling of readily available boronic acids and diazo compounds has emerged recently as a powerful metal-free carbon–carbon bond forming method. However, the difficulty in forming the unstable diazo compound partner in a mild fashion has hitherto limited their general use and the scope of the transformation. Here, we report the application of oxadiazolines as precursors for the generation of an unstable family of diazo compounds using flow UV photolysis and their first use in divergent protodeboronative and oxidative C(sp2)?C(sp3) cross-coupling processes, with excellent functional-group tolerance.
- Greb, Andreas,Poh, Jian-Siang,Greed, Stephanie,Battilocchio, Claudio,Pasau, Patrick,Blakemore, David C.,Ley, Steven V.
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supporting information
p. 16602 - 16605
(2017/12/13)
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- Optimization of TRPV6 calcium channel inhibitors using a 3D ligand-based virtual screening method
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Herein, we report the discovery of the first potent and selective inhibitor of TRPV6, a calcium channel overexpressed in breast and prostate cancer, and its use to test the effect of blocking TRPV6-mediated Ca2+-influx on cell growth. The inhib
- Simonin, Céline,Awale, Mahendra,Brand, Michael,Van Deursen, Ruud,Schwartz, Julian,Fine, Michael,Kovacs, Gergely,H?fliger, Pascal,Gyimesi, Gergely,Sithampari, Abilashan,Charles, Roch-Philippe,Hediger, Matthias A.,Reymond, Jean-Louis
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supporting information
p. 14748 - 14752
(2016/02/05)
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- A novel process for synthesis of atovaquone
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A stereospecific efficient process for synthesis of atovaquone i.e. trans-2-[4-(4-chlorophenyl)cyclohexyl ]-3-hydroxy-1,4-naphthalenedione and its cis isomer from commercially available raw materials such as α-tetralone and 4-(4-chlorophenyl)cyclohexanone
- Roy, Bhairab N,Singh, Girij P,Lathi, Piyush S,Agrawal, Manoj K,Mitra, Rangan,Trivedi, Anurag
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p. 1299 - 1312
(2014/01/06)
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- Enantioselective baeyer-villiger oxidation: Desymmetrization of meso cyclic ketones and kinetic resolution of racemic 2-arylcyclohexanones
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Catalytic enantioselective Baeyer-Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N'-dioxide-Sc III complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active μ- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Hu, Xiaolei,Lin, Lili,Feng, Xiaoming
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supporting information
p. 17023 - 17026,4
(2012/12/12)
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- Enantioselective baeyer-villiger oxidation: Desymmetrization of meso cyclic ketones and kinetic resolution of racemic 2-arylcyclohexanones
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Catalytic enantioselective Baeyer-Villiger (BV) oxidations of racemic and meso cyclic ketones were achieved in the presence of chiral N,N'-dioxide-Sc III complex catalysts. The BV oxidations of prochiral cyclohexanones and cyclobutanones afforded series of optically active μ- and γ-lactones, respectively, in up to 99% yield and 95% ee. Meanwhile, the kinetic resolution of racemic 2-arylcyclohexanones was also realized via an abnormal BV oxidation. Enantioenriched 3-aryloxepan-2-ones, whose formation is counter to the migratory aptitude, were obtained preferentially. Both the lactones and the unreacted ketones were obtained with high ee values.
- Zhou, Lin,Liu, Xiaohua,Ji, Jie,Zhang, Yuheng,Hu, Xiaolei,Lin, Lili,Feng, Xiaoming
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supporting information
p. 17023 - 17026
(2013/01/15)
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- NOVEL METHOD FOR PREPARATION OF ATOVAQUONE
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Provided is a process of preparation of 2-[trans,-4-(4'-chlorophenyl)cyclohexyl]-3-hydroxy- 1,4-naphthoquinone, i.e. Atovaquone [I] which is cost effective, green, and eco-friendly process, without separation of any diastereomers or geometric isomers of intermediates obtained during the reactions. Also provided is separation of 'cis' and 'trans ' isomer of intermediates VI, VII and VIII through selective crystallization in an appropriate solvent. A method for converting 2-[cis,-4-(4'-chlorophenyl)cyclohexyl]-3-hydroxy-1,4-naphthoquinone to 2-[trans-4-(4'-chlorophenyl)cyclohexyl]-3-hydroxy-l,4-naphthoquinone in presence of Lewis/ Bronsted acid is also provided. A process for preparation of compound 2-(4-(4- chlorophenyl)- 1 -hydroxy cyclohexyl)-3,4-dihydronaphthalen- 1 (2H)-one [IV] comprising condensation of (1,2-dihydronaphthalen-4-yloxy)trimethylsilane [II] with 4-(4- chlorophenyl)cyclohexanone [III] in presence of Lewis acid in organic solvent. The invention also encompasses a highly efficient and atomeconomic process for synthesis of compound [III] i.e. 4-(4-chlorophenyl)cyclohexanone as well as a process for synthesis of 2-[cis-4-(4'- chlorophenyl)cyclohexyl]-3-hydroxy-l,4-naphthoquinone. Further provided is a process for isomerization of cis- Atovaquone i.e. 2-[cis-4-(4'-chlorophenyl)cyclohexyl]-3-hydroxy-l,4- naphthoquinone to tnms-Atovaquone i.e. 2-[trans-4-(4'-chlorophenyl)cyclohexyl]-3- hydroxy- 1,4-naphthoquinone in presence of Lewis acid.
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Page/Page column 37-38
(2012/12/13)
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- Discovery of 1-amino-4-phenylcyclohexane-1-carboxylic acid and its influence on agonist selectivity between human melanocortin-4 and -1 receptors in linear pentapeptides
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Linear pentapeptides (Penta-cis-Apc-DPhe-Arg-Trp-Gly-NH2) containing 1-amino-4-phenylcyclohexane-1-carboxylic acid (cis-Apc) and substituted Apc are potent hMC4R agonists and they are inactive or weakly active in hMC1R, hMC3R, and hMC5R agonist assays. This study, together with our earlier report on 5-BrAtc, demonstrated the importance of replacing His 6 with phenyl-containing rigid templates in achieving good hMC4R agonist potency and selectivity against hMC1R in linear pentapeptides.
- Chu, Xin-Jie,Bartkovitz, David,Danho, Waleed,Swistok, Joseph,Cheung, Adrian Wai-Hing,Kurylko, Grazyna,Rowan, Karen,Yeon, Mitch,Franco, Lucia,Qi, Lida,Chen, Li,Yagaloff, Keith
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p. 4910 - 4914
(2007/10/03)
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- Synthesis of atovaquone
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A short synthesis of atovaquone I is achieved via the radical coupling of the trans-1,4-substituted cyclohexyl mono-oxalate 2 and 2- chloronapthoquinone under phase transfer conditions.
- Williams, David R.,Clark, Michael P.
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p. 7629 - 7632
(2007/10/03)
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