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Start Over Author "Dong, Guangbin" Journal angewandte chemie
46 results on '"Dong, Guangbin"'

1. Beyond Tertiary Amines: Introducing Secondary Amines by Palladium/Norbornene‐Catalyzed Ortho Amination.

Author

Liu, Xin, Zhu, Qi, and Dong, Guangbin

Subjects
AMINATION, SECONDARY amines, TERTIARY amines, ARYL iodides, AMINO group, BIOCHEMICAL substrates, PHOSPHINES
Abstract

Since the discovery of the palladium/norbornene (Pd/NBE)‐catalyzed ortho amination in 2013, escaping the limitation of only yielding tertiary anilines has been a long‐standing challenge. Here, we describe that, by carefully choosing the phosphine ligand and NBE mediator, the installation of a N‐mono‐alkylamino group becomes feasible. The reaction tolerates a wide range of aryl iodide substrates and various N‐mono‐tertiary alkylamine‐derived electrophiles. Both ipso alkenylation and alkynylation can be realized. The synthetic utility of this method is exemplified by the formation of primary amino group via selective deprotection and streamlined access to N‐heterocycles. Preliminary success of installing a bulky N‐secondary alkylamino group and a mechanistic understanding of the decomposition pathways of mono N‐alkylamine electrophiles have been obtained. [ABSTRACT FROM AUTHOR]

Published
2024
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34. Palladium‐Catalyzed γ‐C(sp3)−H Arylation of Thiols by a Detachable Protecting/Directing Group.

Author

Jin, Likun, Wang, Jianchun, and Dong, Guangbin

Subjects
PALLADIUM, THIOLS, FUNCTIONAL groups, SULFOXIDES, SILOXANES
Abstract

Abstract: Reported herein is a palladium‐catalyzed, directed γ‐C(sp3)−H arylation of protected thiols. The key is to utilize Michael acceptors as a dual reagent to install a protecting/directing group on thiols by a thiol‐Michael click reaction, and remove it later under basic conditions. The C−H arylation proceeds with high functional‐group tolerance and the deprotected thiols can be further transformed into other sulfur‐containing compounds. This unique mode of activation could open the door for site‐selective functionalization of thiols or other sulfur‐containing compounds at unactivated positions. [ABSTRACT FROM AUTHOR]

Published
2018
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35. Intramolecular Acetyl Transfer to Olefins by Catalytic C−C Bond Activation of Unstrained Ketones.

Author

Rong, Zi‐Qiang, Lim, Hee Nam, and Dong, Guangbin

Subjects
ACETYL compounds, RHODIUM catalysts, INTRAMOLECULAR catalysis, ALKENES, CARBON-carbon bonds, ACTIVATION (Chemistry), KETONES
Abstract

A rhodium-catalyzed intramolecular acetyl-group transfer has been achieved through a 'cut and sew' process. The challenge arises from the existence of different competitive pathways. Preliminary success has been achieved with unstrained enones that contain a biaryl linker. The use of an electron-rich N-heterocycilc carbene (NHC) ligand is effective to inhibit undesired β-hydrogen elimination. Various 9,10-dihydrophenanthrene derivatives can be prepared with excellent functional-group compatibility. The 13C-labelling study suggests that the reaction begins with cleavage of the unstrained C−C bond, followed by migratory insertion and reductive elimination. [ABSTRACT FROM AUTHOR]

Published
2018
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42. Catalytic C(sp3)−H Arylation of Free Primary Amines with an exo Directing Group Generated In Situ.

Author

Xu, Yan, Young, Michael C., Wang, Chengpeng, Magness, David M., and Dong, Guangbin

Subjects
ARYLATION, AMINES, METHYLENE group, CATALYSIS, FEASIBILITY studies
Abstract

Herein, we report the palladium-catalyzed direct arylation of unactivated aliphatic C−H bonds in free primary amines. This method takes advantage of an exo-imine-type directing group (DG) that can be generated and removed in situ. A range of unprotected aliphatic amines are suitable substrates, undergoing site-selective arylation at the γ-position. Methyl as well as cyclic and acyclic methylene groups can be activated. Furthermore, when aniline-derived substrates were used, preliminary success with δ-C−H arylation was achieved. The feasibility of using the DG component in a catalytic fashion was also demonstrated. [ABSTRACT FROM AUTHOR]

Published
2016
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43. Ortho CH Acylation of Aryl Iodides by Palladium/Norbornene Catalysis.

Author

Dong, Zhe, Wang, Jianchun, Ren, Zhi, and Dong, Guangbin

Subjects
ACYLATION, ARYL iodides, CATALYSIS, PALLADIUM catalysts, ACYL cations, ANHYDRIDES
Abstract

Reported herein is a palladium/norbornene-catalyzed ortho-arene acylation of aryl iodides by a Catellani-type CH functionalization. This transformation is enabled by isopropyl carbonate anhydrides, which serve as both an acyl cation equivalent and a hydride source. [ABSTRACT FROM AUTHOR]

Published
2015
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