The Experts below are selected from a list of 1257 Experts worldwide ranked by ideXlab platform
Alison J. Frontier - One of the best experts on this subject based on the ideXlab platform.
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New Twists in Nazarov Cyclization Chemistry.
Accounts of chemical research, 2020Co-Authors: Alison J. Frontier, Jackson J. HernandezAbstract:ConspectusThe defining feature of the Nazarov Cyclization is a 4π-conrotatory electroCyclization, resulting in the stereospecific formation of functionalized cyclopentanones. The reaction provides ...
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Stereochemical Relay through a Cationic Intermediate: Helical Preorganization Dictates Direction of Conrotation in the halo-Nazarov Cyclization.
Organic letters, 2020Co-Authors: Georgios Alachouzos, Connor Holt, Alison J. FrontierAbstract:A stereocontrolled halo-Prins/halo-Nazarov Cyclization protocol is reported, where chiral information from a secondary alcohol is relayed through several intermediates yielding halocyclopentene pro...
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leveraging the halo Nazarov Cyclization for the chemodivergent assembly of functionalized haloindenes and indanones
Journal of the American Chemical Society, 2019Co-Authors: Connor Holt, Georgios Alachouzos, Alison J. FrontierAbstract:In this report, we describe a halo-Prins/aryl halo-Nazarov Cyclization strategy that employs readily available starting materials, inexpensive reagents, and convenient reaction procedures to generate functionalized haloindenes and indanones. The scope and limitations of the method are outlined, demonstrating that aromatic systems readily react under mild, catalytic conditions when this strategy is implemented. Furthermore, we present both experimental and computational data supporting the notion that Cyclizations of 3-halopentadienyl cationic intermediates are more kinetically accessible, as well as more thermodynamically favorable, than Cyclizations of the analogous 3-oxypentadienyl cationic systems. The energetic advantage imparted by the halo-Nazarov Cyclization design was found to be especially valuable in the Cyclizations of arylallyl cationic intermediates, which require disruption of aromaticity.
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Leveraging the Halo-Nazarov Cyclization for the Chemodivergent Assembly of Functionalized Haloindenes and Indanones
2019Co-Authors: Connor Holt, Georgios Alachouzos, Alison J. FrontierAbstract:In this report, we describe a halo-Prins/aryl halo-Nazarov Cyclization strategy that employs readily available starting materials, inexpensive reagents, and convenient reaction procedures to generate functionalized haloindenes and indanones. The scope and limitations of the method are outlined, demonstrating that aromatic systems readily react under mild, catalytic conditions when this strategy is implemented. Furthermore, we present both experimental and computational data supporting the notion that Cyclizations of 3-halopentadienyl cationic intermediates are more kinetically accessible, as well as more thermodynamically favorable, than Cyclizations of the analogous 3-oxypentadienyl cationic systems. The energetic advantage imparted by the halo-Nazarov Cyclization design was found to be especially valuable in the Cyclizations of arylallyl cationic intermediates, which require disruption of aromaticity
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Enantioselective Nazarov Cyclization Catalyzed by a Cinchona Alkaloid Derivative.
ChemInform, 2015Co-Authors: Yu-wen Huang, Alison J. FrontierAbstract:Diene-diones of type (I) undergo an 1,6-addition/Nazarov Cyclization/elimination reaction in the presence of Hatkeyama′s chiral cinchona alkaloid catalyst to give functionalized cyclopentenones in good yields and enantioselectivities.
Marcus A Tius - One of the best experts on this subject based on the ideXlab platform.
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Catalytic Enantioselective Nazarov Cyclization
European Journal of Organic Chemistry, 2017Co-Authors: Anais Jolit, Cody F. Dickinson, Kei Kitamura, Patrick M. Walleser, Glenn P. A. Yap, Marcus A TiusAbstract:The detailed account of an asymmetric Nazarov Cyclization that leads to α-hydroxycyclopentenones bearing either vicinal, all-carbon atom quaternary centers, or vicinal quaternary and tertiary centers is described. The all-aliphatic examples represent the greatest challenge as the dienone starting materials are not activated toward Cyclization by an aryl group. The rational design and optimization of the substrates in parallel with the optimization of the chiral Bronsted acid catalyst is also described as well as a series of diastereoselective transformations of a fully substituted cyclopentenone product.
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catalytic enantioselective Nazarov Cyclization construction of vicinal all carbon atom quaternary stereocenters
ChemInform, 2014Co-Authors: Anais Joli, Gle P A Yap, Patrick M Wallese, Marcus A TiusAbstract:This asymmetric Nazarov Cyclization procedure of fully substituted dienones provides cyclopentenones with vicinal quaternary stereocenters in high optical purity and as single diastereoisomers.
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catalytic enantioselective Nazarov Cyclization construction of vicinal all carbon atom quaternary stereocenters
Angewandte Chemie, 2014Co-Authors: Anais Joli, Gle P A Yap, Marcus A Tius, Patrick M WalleseAbstract:The diastereoselective asymmetric synthesis of vicinal all-carbon-atom quaternary stereocenters is a challenging problem in organic synthesis for which only few solutions have been described. A catalytic asymmetric Nazarov Cyclization of fully substituted dienones that provides cyclopentenone derivatives with vicinal quaternary stereocenters in high optical purity and as single diastereoisomers is now reported.
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Catalytic Enantioselective Nazarov Cyclization: Construction of Vicinal All‐Carbon‐Atom Quaternary Stereocenters
Angewandte Chemie (International ed. in English), 2014Co-Authors: Anais Jolit, Patrick M. Walleser, Glenn P. A. Yap, Marcus A TiusAbstract:The diastereoselective asymmetric synthesis of vicinal all-carbon-atom quaternary stereocenters is a challenging problem in organic synthesis for which only few solutions have been described. A catalytic asymmetric Nazarov Cyclization of fully substituted dienones that provides cyclopentenone derivatives with vicinal quaternary stereocenters in high optical purity and as single diastereoisomers is now reported.
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Allene ether Nazarov Cyclization
Chemical Society reviews, 2013Co-Authors: Marcus A TiusAbstract:The ease of synthesis and the exceptional reactivity of alkoxyallenes has led to their use in a large number of highly diverse applications. This Report describes their use in various versions of the allene ether Nazarov Cyclization. Following a brief introduction to the Nazarov Cyclization (Section 1), the oxidative Cyclization of vinyl alkoxyallenes is discussed first (Section 2). Nazarov Cyclizations of α-alkoxyallenyl vinyl ketones and of α-alkoxyallenyl vinyl tertiary carbinols are covered (Section 3). The discovery and the subsequent rational design of acetals that serve as chiral auxiliaries on the allene in highly enantioselective Nazarov Cyclizations is explained (Section 4). Interrupted Nazarov Cyclizations of alkoxyallenes that are generated in situ from the isomerization of propargyl ethers on solid supports are discussed, including the evolution of a highly diastereoselective, chiral auxiliary controlled version of the reaction. Some applications of the methodology to natural products total synthesis have been included so as to provide the reader with benchmarks with which to judge the utility of the methodology.
Heyi Zhang - One of the best experts on this subject based on the ideXlab platform.
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Nickel/Copper Dual Catalysis for Sequential Nazarov Cyclization/Decarboxylative Aldol Reaction.
Organic letters, 2018Co-Authors: Heyi ZhangAbstract:A nickel/copper cocatalyzed sequential Nazarov Cyclization/decarboxylative aldol reaction is reported. Various β-hydroxycyclopentenones containing three contiguous stereocenters were prepared in good yields with high diastereoselectivities. A gram-scale reaction and further derivatizations were easily achieved to highlight the synthetic utility of this transformation. Preliminary attempts for sequential asymmetric transformation were also conducted.
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enantioselective cobalt catalyzed sequential Nazarov Cyclization electrophilic fluorination access to chiral α fluorocyclopentenones
Organic Letters, 2018Co-Authors: Heyi Zhang, Biao Cheng, Zhan LuAbstract:A newly designed thiazoline iminopyridine ligand for enantioselective cobalt-catalyzed sequential Nazarov Cyclization/electrophilic fluorination was developed. Various chiral α-fluorocyclopentenones were prepared with good yields and diastereo- and enantioselectivities. Further derivatizations could be easily carried out to provide chiral cyclopentenols with three contiguous stereocenters. Furthermore, a direct deesterification of fluorinated products could afford chiral α-single fluorine-substituted cyclopentenones.
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Enantioselective Cobalt-Catalyzed Sequential Nazarov Cyclization/Electrophilic Fluorination: Access to Chiral α-Fluorocyclopentenones
Organic Letters, 2018Co-Authors: Heyi Zhang, Biao Cheng, Zhan LuAbstract:A newly designed thiazoline iminopyridine ligand for enantioselective cobalt-catalyzed sequential Nazarov Cyclization/electrophilic fluorination was developed. Various chiral α-fluorocyclopentenones were prepared with good yields and diastereo- and enantioselectivities. Further derivatizations could be easily carried out to provide chiral cyclopentenols with three contiguous stereocenters. Furthermore, a direct deesterification of fluorinated products could afford chiral α-single fluorine-substituted cyclopentenones.
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Nickel-catalyzed enantioselective sequential Nazarov Cyclization/decarboxylation
Organic Chemistry Frontiers, 2018Co-Authors: Heyi ZhangAbstract:The nickel-catalyzed enantioselective sequential Nazarov Cyclization/decarboxylation has been developed. The use of chiral oxazoline iminopyridine and metal perchlorate allows the enantioselective decarboxylative electroCyclization of divinyl ketones bearing an α-ester group to afford chiral cyclopentenones in good yields with excellent enantioselectivities. Various derivatizations could be easily carried out to deliver chiral polysubstituted cyclopentenes. Primary mechanistic studies demonstrated that nickel-catalyzed asymmetric Nazarov Cyclization was followed by nickel-promoted decarboxylation.
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Nickel/Copper Dual Catalysis for Sequential Nazarov Cyclization/Decarboxylative Aldol Reaction
2018Co-Authors: Heyi ZhangAbstract:A nickel/copper cocatalyzed sequential Nazarov Cyclization/decarboxylative aldol reaction is reported. Various β-hydroxycyclopentenones containing three contiguous stereocenters were prepared in good yields with high diastereoselectivities. A gram-scale reaction and further derivatizations were easily achieved to highlight the synthetic utility of this transformation. Preliminary attempts for sequential asymmetric transformation were also conducted
Fu-min Zhang - One of the best experts on this subject based on the ideXlab platform.
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Organocatalytic Asymmetric Tandem Nazarov Cyclization/Semipinacol Rearrangement: Rapid Construction of Chiral Spiro[4.4]nonane-1,6-diones
Journal of the American Chemical Society, 2015Co-Authors: Bin-miao Yang, Pei-jun Cai, Zhi-min Chen, Shuang-hu Wang, Shao-hua Wang, Fu-min ZhangAbstract:A novel organocatalytic asymmetric tandem Nazarov Cyclization/semipinacol rearrangement reaction using "unactivated" substrates has been developed, generating a series of chiral spiro[4.4]nonane-1,6-diones in up to 96% yield and 97% enantiomeric excess. Significantly, it is the first direct example for asymmetric synthesis of cyclopentanones with four stereocenters using Nazarov Cyclization. DFT calculations have been applied to understand the reaction mechanism, stereochemistry, and substituent effects.
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organocatalytic asymmetric tandem Nazarov Cyclization semipinacol rearrangement rapid construction of chiral spiro 4 4 nonane 1 6 diones
Journal of the American Chemical Society, 2015Co-Authors: Bin-miao Yang, Pei-jun Cai, Zhi-min Chen, Shuang-hu Wang, Shao-hua Wang, Fu-min ZhangAbstract:A novel organocatalytic asymmetric tandem Nazarov Cyclization/semipinacol rearrangement reaction using “unactivated” substrates has been developed, generating a series of chiral spiro[4.4]nonane-1,6-diones in up to 96% yield and 97% enantiomeric excess. Significantly, it is the first direct example for asymmetric synthesis of cyclopentanones with four stereocenters using Nazarov Cyclization. DFT calculations have been applied to understand the reaction mechanism, stereochemistry, and substituent effects.
Qun Liu - One of the best experts on this subject based on the ideXlab platform.
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tandem Nazarov Cyclization halovinylation of divinyl ketones under vilsmeier conditions synthesis of highly substituted cyclopentadienes
ChemInform, 2010Co-Authors: Mang Wang, Hongjuan Yuan, Feng Han, Qun LiuAbstract:A novel tandem Nazarov Cyclization—halovinylation strategy is developed for the synthesis of highly substituted cyclopentadienes.
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Tandem Nazarov Cyclization—Halovinylation of Divinyl Ketones under Vilsmeier Conditions: Synthesis of Highly Substituted Cyclopentadienes.
ChemInform, 2010Co-Authors: Mang Wang, Hongjuan Yuan, Feng Han, Qun LiuAbstract:A novel tandem Nazarov Cyclization—halovinylation strategy is developed for the synthesis of highly substituted cyclopentadienes.
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Tandem Nazarov Cyclization-halovinylation of divinyl ketones under Vilsmeier conditions: synthesis of highly substituted cyclopentadienes.
Chemical communications (Cambridge, England), 2010Co-Authors: Mang Wang, Hongjuan Yuan, Feng Han, Qun LiuAbstract:A new Vilsmeier reagent-mediated Nazarov Cyclization-halovinylation reaction of divinyl ketones was developed to provide a straightforward method for the synthesis of highly substituted cyclopentadienes with the advantages of simplicity of execution, readily available substrates, cheap reagents, and broad range of potential products and applications.
