Dienylation of Unfunctionalized Arenes with 1,6-Diynes via Rhodium-Catalyzed Directing Group-Free C-H Bond Activation

Synthesis ◽  
2020 ◽  
Author(s):  
Hiroto Takahashi ◽  
Yusaku Honjo ◽  
Yu Shibata ◽  
Yuki Nagashima ◽  
Ken Tanaka
Keyword(s):  
Bond Activation ◽  
Catalytic Amount ◽  
Mechanistic Studies ◽  
Silver Carbonate ◽  
Stoichiometric Amount ◽  
Directing Group

It has been established that the dienylation of unfunctionalized arenes with 1,6-diynes, possessing aryl groups at the diyne termini, proceeds to give the corresponding dienylated arenes in the presence of a catalytic amount of an electron-deficient cyclopentadienyl rhodium(III) complex, [CpERhCl2]2 (1), and a stoichiometric amount of silver carbonate. Experimental and theoretical mechanistic studies revealed that an in-situ generated CpERh(I) complex might catalyze the present dienylation reaction.

ChemInform Abstract: Rhodium(III)-Catalyzed in situ Oxidizing Directing Group-Assisted C-H Bond Activation and Olefination: A Route to 2-Vinylanilines.

ChemInform ◽  
2015 ◽  
Vol 46 (30) ◽  
pp. no-no
Author(s):  
Krishnamoorthy Muralirajan ◽  
Radhakrishnan Haridharan ◽  
Sekar Prakash ◽  
Chien-Hong Cheng
Keyword(s):  
Bond Activation ◽  
Directing Group

Step-Economical C–H Activation Reactions Directed by In Situ Amidation

Synthesis ◽  
2020 ◽  
Vol 52 (21) ◽  
pp. 3211-3218
Author(s):  
Yunyun Liu ◽  
Baoli Zhao
Keyword(s):  
Transition Metal ◽  
Bond Activation ◽  
Short Review ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Directing Group ◽  
Crude Material

Owing to the inherent ability of amides to chelate transition-metal catalysts, amide-directed C–H activation reactions constitute a major tactic in directed C–H activation reactions. While the conventional procedures for these reactions usually involve prior preparation and purification of amide substrates before the C–H activation, the step economy is actually undermined by the operation of installing the directing group (DG) and related substrate purification. In this context, directed C–H activation via in situ amidation of the crude material provides a new protocol that can significantly enhance the step economy of amide-directed C–H activation. In this short review, the advances in C–H bond activation reactions mediated or initiated by in situ amidation are summarized and analyzed.1 Introduction2 In Situ Amidation in Aryl C–H Bond Activation3 In Situ Amidation in Alkyl C–H Bond Activation4 Annulation Reactions via Amidation-Mediated C–H Activation5 Remote C–H Activation Mediated by Amidation6 Conclusion

scholarly journals Mechanistic Studies of Pd(II)-Catalyzed E/Z Isomerization of Unactivated Alkenes: Evidence for a Monometallic Nucleopalladation Pathway

2020 ◽  
Author(s):  
Rei Matsuura ◽  
Malkanthi Karunananda ◽  
Mingyu Liu ◽  
Nhi Nguyen ◽  
Donna Blackmond ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Kinetic Analysis ◽  
Kinetic Modeling ◽  
Spectroscopic Studies ◽  
Mechanistic Studies ◽  
Common Process ◽  
Directing Group

Pd(II)-catalyzed <i>E</i>/<i>Z</i> isomerization of alkenes is a common process—yet is largely uncharacterized, particularly with non-conjugated alkenes. In this work, the mechanism of Pd(II)-catalyzed <i>E</i>/<i>Z</i> isomerization of unactivated olefins containing an aminoquinoline-based amide directing group is probed using <i>in situ</i> kinetic analysis, spectroscopic studies, kinetic modeling, and DFT calculations. The directing group allows for stabilization and monitoring of previously undetectable intermediates. Collectively, the data are consistent with isomerization occurring through a monometallic nucleopalladation mechanism.

Rhodium(III)-Catalyzed in situ Oxidizing Directing Group- Assisted CH Bond Activation and Olefination: A Route to 2-Vinylanilines

2015 ◽  
Vol 357 (4) ◽  
pp. 761-766 ◽  
Author(s):  
Krishnamoorthy Muralirajan ◽  
Radhakrishnan Haridharan ◽  
Sekar Prakash ◽  
Chien-Hong Cheng
Keyword(s):  
Bond Activation ◽  
Directing Group

A Review on Sulfur-Directed C−H Bond Activation

2020 ◽  
Vol 17 ◽  
Author(s):  
Xuchong Tang ◽  
Yingwei Zhao
Keyword(s):  
Transition Metal ◽  
Electron Donor ◽  
Bond Activation ◽  
Bond Formation ◽  
Metal Catalysts ◽  
Transition Metal Catalysts ◽  
Directing Group ◽  
Metal Catalyzed ◽  
Sulfur Containing

: Transition-metal-catalyzed C−H bond activation employing a directing group is becoming a powerful tool to access C−C or C−hetero bond formation. Oxygen and nitrogen atoms are commonly applied as the electron donor for these directing groups. In contrast, there are only few studies on sulfur-containing groups, probably due to their toxicity to transition-metal catalysts. Nowadays a large amount of C−H activation reactions directed by sulfur-containing auxiliary groups have been successfully achieved. Because these groups can be facilely removed or modified in situ or in further steps, they are of great value in creative synthetic strategies. This paper reviews recent advances in the studies using thioether, thiol/thiophenol/disulfide, sulfoxide, and thiocarbonyl as directing groups for intermolecular C−H functionalizations as well as intramolecular oxidative annulations.

Rhodium(III)-Catalyzed C–H Activation/Alkylation of Diazabicyclic Olefins with Aryl Ketones: Facile Synthesis of Functionalized Cyclopentenes

Synlett ◽  
2018 ◽  
Vol 29 (15) ◽  
pp. 2023-2026 ◽  
Author(s):  
K. Radhakrishnan ◽  
P. Santhini ◽  
Greeshma Gopalan ◽  
A. Smrithy
Keyword(s):  
Ammonium Acetate ◽  
Bond Activation ◽  
Facile Synthesis ◽  
Reaction Proceeds ◽  
Aryl Ketones ◽  
Directing Group ◽  
Aryl Ketone

A facile synthesis of biologically important trans-functionalized cyclopentenes by a mild Rh(III)-catalyzed alkylation of strained ­diazabicyclic olefins with aryl ketones in the presence of ammonium ­acetate has been developed. The reaction proceeds through C–H bond activation of the aryl ketone groups by transforming them in to an ­autocleavable directing group, such as in situ-formed imine.

scholarly journals Mechanistic Studies of Pd(II)-Catalyzed E/Z Isomerization of Unactivated Alkenes: Evidence for a Monometallic Nucleopalladation Pathway

2020 ◽  
Author(s):  
Rei Matsuura ◽  
Malkanthi Karunananda ◽  
Mingyu Liu ◽  
Nhi Nguyen ◽  
Donna Blackmond ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Kinetic Analysis ◽  
Kinetic Modeling ◽  
Spectroscopic Studies ◽  
Mechanistic Studies ◽  
Common Process ◽  
Directing Group

Pd(II)-catalyzed <i>E</i>/<i>Z</i> isomerization of alkenes is a common process—yet is largely uncharacterized, particularly with non-conjugated alkenes. In this work, the mechanism of Pd(II)-catalyzed <i>E</i>/<i>Z</i> isomerization of unactivated olefins containing an aminoquinoline-based amide directing group is probed using <i>in situ</i> kinetic analysis, spectroscopic studies, kinetic modeling, and DFT calculations. The directing group allows for stabilization and monitoring of previously undetectable intermediates. Collectively, the data are consistent with isomerization occurring through a monometallic nucleopalladation mechanism.

Imine as a Linchpin Approach for Distal C(sp2)–H Functionalization

2020 ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligand ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

<p>Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal <i>ortho</i>-, distal <i>meta</i>- and <i>para</i>-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(<i>sp<sup>2</sup></i>)-H functionalization <i>via</i> reversible imine formation. By overruling facile proximal C-H bond activation by imine-<i>N</i> atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.</p>

Synthetic and Mechanistic Studies of a Versatile Heteroaryl Thioether Directing Group for Pd(II) Catalysis

2019 ◽  
Author(s):  
Andrew Romine ◽  
Kin Yang ◽  
Malkanthi Karunananda ◽  
Jason Chen ◽  
Keary Engle
Keyword(s):  
Mechanistic Studies ◽  
Salvianolic Acid ◽  
Wide Range ◽  
Computational Data ◽  
Synthetic Utility ◽  
Directing Group ◽  
High Yields ◽  
Julia Olefination ◽  
Reaction Progress Kinetic Analysis

A weakly coordinating monodentate heteroaryl thioether directing group has been developed for use in Pd(II) catalysis to orchestrate key elementary steps in the catalytic cycle that require conformational flexibility in a manner that is difficult to accomplish with traditional strongly coordinating directing groups. This benzothiazole thioether, (BT)S, directing group can be used to promote oxidative Heck reactivity of internal alkenes providing a wide range of products in moderate to high yields. To demonstrate the broad applicability of this directing group, arene C–H olefination was also successfully developed. Reaction progress kinetic analysis provides insights into the role of the directing group in each reaction, which is supplemented with computational data for the oxidative Heck reaction. Furthermore, this (BT)S directing group can be transformed into a number of synthetically useful functional groups, including a sulfone for Julia olefination, allowing it to serve as a “masked olefin” directing group in synthetic planning. In order to demonstrate this synthetic utility, natural products (+)-salvianolic acid A and salvianolic acid F are formally synthesized using the (BT)S directed C–H olefination as the key step.

scholarly journals PCl3-mediated transesterification and aminolysis of tert-butyl esters via acid chloride formation

2021 ◽  
pp. 174751982098753
Author(s):  
Xiaofang Wu ◽  
Lei Zhou ◽  
Fangshao Li ◽  
Jing Xiao
Keyword(s):  
Acid Chloride ◽  
Bioactive Molecules ◽  
Mechanistic Studies ◽  
One Pot ◽  
Tert Butyl ◽  
Butyl Esters

A PCl3-mediated conversion of tert-butyl esters into esters and amides in one-pot under air is developed. This novel protocol is highlighted by the synthesis of skeletons of bioactive molecules and gram-scale reactions. Mechanistic studies revealed that this transformation involves the formation of an acid chloride in situ, which is followed by reactions with alcohols or amines to afford the desired products.

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