The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Guangbin Dong - One of the best experts on this subject based on the ideXlab platform.
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kinetic resolution via rh catalyzed c c activation of cyclobutanones at room temperature
Journal of the American Chemical Society, 2019Co-Authors: Lin Deng, Siu Yin Lee, Chengpeng Wang, Peng Liu, Guangbin DongAbstract:Herein we describe the development of a highly selective kinetic resolution of cyclobutanones via a Rh-catalyzed “cut-and-sew” reaction with selectivity factor up to 785. This reaction takes place ...
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4 1 vs 4 2 catalytic intramolecular coupling between cyclobutanones and trisubstituted allenes via c c activation
Journal of the American Chemical Society, 2015Co-Authors: Xuan Zhou, Guangbin DongAbstract:Herein we describe a rhodium-catalyzed (4+1) cyclization between cyclobutanones and allenes, which provides a distinct [4.2.1]-bicyclic skeleton containing two quaternary carbon centers. The reaction involves C–C activation of cyclobutanones and employs allenes as a one-carbon unit. A variety of functional groups can be tolerated, and a diverse range of polycyclic scaffolds can be accessed. Excellent enantioselectivity can be obtained, which is enabled by a TADDOL-derived phosphoramidite ligand. The bridged bicyclic products can be further functionalized or derivatized though simple transformations.
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Rh-catalyzed reagent-free ring expansion of Cyclobutenones and benzoCyclobutenones
Chemical science, 2015Co-Authors: Peng‐hao Chen, Joshua D. Sieber, Chris H. Senanayake, Guangbin DongAbstract:Here we report a reagent-free rhodium-catalyzed ring-expansion reaction via C–C cleavage of Cyclobutenones. A variety of poly-substituted cyclopentenones and 1-indanones can be synthesized from simple Cyclobutenones and benzoCyclobutenones. The reaction condition is near pH neutral without additional oxidants or reductants. The potential for developing a dynamic kinetic asymmetric transformation of this reaction has also been demonstrated. Further study supports the proposed pathway involving Rh-insertion into the cyclobutenone C–C bond, followed by β-hydrogen elimination, olefin insertion and reductive elimination.
Francesco Secci - One of the best experts on this subject based on the ideXlab platform.
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organocatalytic asymmetric condensation keto enol tautomerization tandem reaction access to cyclobutanone α amino acid ester derivatives
Asian Journal of Organic Chemistry, 2014Co-Authors: Angelo Frongia, Nicola Melis, Ilaria Serra, Francesco Secci, Pier Paolo Piras, Pierluigi CaboniAbstract:A practical method for the synthesis of optically active α-amino cyclobutanones has been developed, via an organocatalytic asymmetric condensation reaction between racemic 2-hydroxycyclobutanone and chiral N-alkyl-α-amino acid ester derivatives.
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unexpected formation of optically active 4 substituted 5 hydroxy γ lactams by organocatalyzed reaction of 3 substituted cyclobutanones with nitrosobenzene
ChemInform, 2011Co-Authors: Francesca Capitta, Angelo Frongia, Pier Paolo Piras, Jean Ollivier, Francesco SecciAbstract:Treatment of Cyclobutenones with nitrosobenzene in the presence of chiral amine catalysts does not produce the expected derivatives (IV) but lactams of type (III).
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unexpected formation of opticallyactive 4 substituted 5 hydroxy γ lactams by organocatalyzedreaction of 3 substituted cyclobutanones with nitrosobenzene
Synlett, 2011Co-Authors: Francesca Capitta, Angelo Frongia, Pier Paolo Piras, Jean Ollivier, Francesco SecciAbstract:An organocatalyzed enantioselective desymmetrization reaction for converting 3-substituted cyclobutanones into 4-substituted 5-hydroxy-γ-lactams is presented. This involves a ring-expanding O-nitroso aldol―cyclization domino sequence. This synthetic protocol provides access to five-membered ring systems in good yields with the generation of two new stereogenic centers.
Yuji Matsuya - One of the best experts on this subject based on the ideXlab platform.
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efficient approach to 1 2 diazepines via formal diazomethylene insertion into the c c bond of Cyclobutenones
Organic Letters, 2012Co-Authors: Kenji Sugimoto, Rie Hayashi, Hideo Nemoto, Naoki Toyooka, Yuji MatsuyaAbstract:Efficient monocyclic 1,2-diazepine formation via a tandem electrocyclization reaction of Cyclobutenones with lithiodiazoacetate is demonstrated. The reaction proceeds through an oxy anion-accelerated 4π-ring opening of cyclobutene followed by an 8π-ring closure of the resultant oxy anion-substituted diazo-diene under mild conditions to furnish a 1,2-diazepine via formal diazomethylene insertion into the C–C bond of cyclobutenone.
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Efficient Approach to 1,2-Diazepines via Formal Diazomethylene Insertion into the C–C bond of Cyclobutenones
Organic letters, 2012Co-Authors: Kenji Sugimoto, Rie Hayashi, Hideo Nemoto, Naoki Toyooka, Yuji MatsuyaAbstract:Efficient monocyclic 1,2-diazepine formation via a tandem electrocyclization reaction of Cyclobutenones with lithiodiazoacetate is demonstrated. The reaction proceeds through an oxy anion-accelerated 4π-ring opening of cyclobutene followed by an 8π-ring closure of the resultant oxy anion-substituted diazo-diene under mild conditions to furnish a 1,2-diazepine via formal diazomethylene insertion into the C–C bond of cyclobutenone.
Masahiro Murakami - One of the best experts on this subject based on the ideXlab platform.
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oxidative addition of a strained c c bond onto electron rich rhodium i at room temperature
Journal of the American Chemical Society, 2013Co-Authors: Yusuke Masuda, Naoki Ishida, Maki Hasegawa, Makoto Yamashita, Kyoko Nozaki, Masahiro MurakamiAbstract:The C–C bond of cyclobutanones undergoes oxidative addition to a T-shape rhodium(I) complex possessing a PBP pincer ligand at room temperature. The remarkable propensity of the rhodium complex for oxidative addition is attributed to the highly electron-donating nature of the boron ligand as well as the unsaturation on the rhodium center.
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atom and step economical pathway to chiral benzobicyclo 2 2 2 octenones through carbon carbon bond cleavage
ChemInform, 2012Co-Authors: Lantao Liu, Naoki Ishida, Masahiro MurakamiAbstract:The asymmetric intramolecular alkene insertion reaction of 3-(2-styryl)cyclobutanones is efficiently catalyzed by Ni(cod)2 in the presence of PAM.
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activation of a cyclobutanone carbon carbon bond over an aldehyde carbon hydrogen bond in the rhodium catalyzed decarbonylation
Chemistry Letters, 2006Co-Authors: Takanori Matsuda, Masanori Shigeno, Masahiro MurakamiAbstract:A rhodium(I)-N-heterocyclic carbene complex achieved a high-yield decarbonylation reaction of cyclobutanones to selectively afford cyclopropanes. With this catalyst, a cyclobutanone having an aldehyde moiety underwent chemoselective decarbonylation of the ketonic carbonyl group with the aldehydic carbonyl group left intact.
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a silyl substituent dictates the pathway of a concerted electrocyclic ring opening of cyclobutene
Journal of Synthetic Organic Chemistry Japan, 2002Co-Authors: Masahiro Murakami, Yasufumi Miyamoto, Yoshihiko ItoAbstract:The previous studies on rhodium chemistry directed us to investigate the substituent effect of silicon on an electrocyclic ring-opening reaction of cyclobutene. It was discovered that a silyl substituent accelerates the reaction and prefers inward rotation, giving the Z-isomer. These intriguing effects were explained by the electron-accepting interactions between the low-lying σ* orbital of the silicon atom and the HOMO orbital of the opening cyclobutene system, possible only in the inward transition state. On the basis of this finding, a novel method for the stereoselective synthesis of functionalized 1,3-butadiene derivatives from Cyclobutenones was developed.
Rick L Danheiser - One of the best experts on this subject based on the ideXlab platform.
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Synthesis of Highly Substituted Quinolines via a Tandem Ynamide Benzannulation/Iodocyclization Strategy
2015Co-Authors: Thomas P Willumstad, Paul D Boudreau, Rick L DanheiserAbstract:A two-stage “tandem strategy” for the regiocontrolled synthesis of very highly substituted quinolines is described. Benzannulation based on the reaction of Cyclobutenones or diazo ketones with N-propargyl-substituted ynamides proceeds via a cascade of several pericyclic reactions to generate multiply substituted aniline derivatives. In the second stage of the tandem strategy, triflate derivatives of the phenolic benzannulation products undergo Larock cyclization upon exposure to iodine to form products that are further elaborated by methods such as palladium-catalyzed coupling to generate quinolines that can be substituted at every position of the bicyclic system
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benzannulation via the reaction of ynamides and vinylketenes application to the synthesis of highly substituted indoles
Journal of Organic Chemistry, 2013Co-Authors: Tin Yiu Lam, Yupu Wang, Rick L DanheiserAbstract:A two-stage “tandem strategy” for the synthesis of indoles with a high level of substitution on the six-membered ring is described. Benzannulation based on the reaction of Cyclobutenones with ynamides proceeds via a cascade of four pericyclic reactions to produce multiply substituted aniline derivatives in which the position ortho to the nitrogen can bear a wide range of functionalized substituents. In the second stage of the tandem strategy, highly substituted indoles are generated via acid-, base-, and palladium-catalyzed cyclization and annulation processes.
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synthesis of highly substituted quinolines via a tandem ynamide benzannulation iodocyclization strategy
ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY, 2010Co-Authors: Thomas P Willumstad, Paul D Boudreau, Rick L DanheiserAbstract:A two-stage “tandem strategy” for the regiocontrolled synthesis of very highly substituted quinolines is described. Benzannulation based on the reaction of Cyclobutenones or diazo ketones with N-propargyl-substituted ynamides proceeds via a cascade of several pericyclic reactions to generate multiply substituted aniline derivatives. In the second stage of the tandem strategy, triflate derivatives of the phenolic benzannulation products undergo Larock cyclization upon exposure to iodine to form products that are further elaborated by methods such as palladium-catalyzed coupling to generate quinolines that can be substituted at every position of the bicyclic system.
