Palladium-Catalyzed Allylation of Polyfluoroarenes with Allylic Pivalates

An efficient 1,5-cyclooctadiene–PdCl2/dicyclohexyl(2′,4′,6′-triisopropylbiphenyl-2-yl)phosphine (XPhos) catalytic system was developed for C–H allylation of polyfluoroarenes with allylic pivalates. The reactions showed excellent functional-group tolerance, good yields, and high regioselectivities. Mechanistic investigations supported a (π-allyl)palladium complex pathway through a directed oxidative addition of the allylic pivalate to palladium, followed by sequential nucleophilic attack by the polyfluorobenzene and reductive elimination. In a gram-scale reaction, a palladium loading of 0.5 mol% was enough to afford the required product in good yield.

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Visible-light-mediated borylation of aryl and alkyl halides with a palladium complex

Organic & Biomolecular Chemistry ◽

10.1039/d0ob00028k ◽

2020 ◽

Vol 18 (23) ◽

pp. 4390-4394

Author(s):

Jia-Hui Zhao ◽

Zhao-Zhao Zhou ◽

Yue Zhang ◽

Xuan Su ◽

Xi-Meng Chen ◽

...

Keyword(s):

Visible Light ◽

Functional Group ◽

Palladium Complex ◽

Alkyl Halides ◽

Palladium Catalyzed ◽

High Yields

Palladium catalyzed visible-light-mediated borylation of inactivated aryl and alkyl halides is reported; the method provided high yields and excellent functional group compatibility.

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Palladium-Catalyzed Anti-Markovnikov Oxidation of Aromatic and Aliphatic Alkenes to Terminal Acetals and Aldehydes

Synthesis ◽

10.1055/s-0040-1706570 ◽

2020 ◽

Author(s):

Yasuyuki Ura

Keyword(s):

Organic Compounds ◽

Catalytic System ◽

Recent Progress ◽

Short Review ◽

Nucleophilic Attack ◽

Reaction Conditions ◽

Terminal Alkenes ◽

Palladium Catalyzed ◽

Substrate Addition ◽

Cyclic Alkenes

AbstractCatalytic anti-Markovnikov (AM) oxidation of terminal alkenes can provide terminally oxyfunctionalized organic compounds. This short review mainly summarizes our recent progress on the Pd-catalyzed AM oxidations of aromatic and aliphatic terminal alkenes to give terminal acetals (oxidative acetalization) and aldehydes (Wacker-type oxidation), along with related reports. These reactions demonstrate the efficacy of the PdCl2(MeCN)2/CuCl/electron-deficient cyclic alkenes/O2 catalytic system. Notably, electron-deficient cyclic alkenes such as p-benzoquinones (BQs) and maleimides are key additives that facilitate nucleophilic attack of oxygen nucleophiles on coordinated terminal alkenes and enhance the AM selectivity. BQs also function to oxidize Pd(0) depending on the reaction conditions. Several other factors that improve the AM selectivity, such as the steric demand of the nucleophiles, slow substrate addition, and halogen-directing groups, are also discussed.1 Introduction2 Anti-Markovnikov Oxidation of Aromatic Alkenes to Terminal Acetals3 Anti-Markovnikov Oxidation of Aromatic Alkenes to Aldehydes4 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Terminal Acetals5 Anti-Markovnikov Oxidation of Aliphatic Alkenes to Aldehydes6 Conclusion

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Selective organometallic syntheses from molecular pools

Pure and Applied Chemistry ◽

10.1351/pac200274010063 ◽

2002 ◽

Vol 74 (1) ◽

pp. 63-68 ◽

Cited By ~ 11

Author(s):

Marta Catellani

Keyword(s):

High Selectivity ◽

Oxidative Addition ◽

Reductive Elimination ◽

Selective Synthesis ◽

Aryl Iodide ◽

Bond Forming ◽

Mild Conditions ◽

Palladium Catalyzed ◽

Selective Alkylation ◽

Sequential Processes

A new methodology is described, consisting of the use of molecular pools in palladium-catalyzed sequential processes occurring under mild conditions with high selectivity. These reactions involve palladacycle formation from aryl iodide, palladium, and norbornene, the latter behaving as a second catalyst that is first incorporated into the metallacycle and expelled at the end of the process. Selective alkylation or arylation of the arene nucleus occurring by oxidative addition/reductive elimination of palladacycles are coupled, after norbornene expulsion, with CH or CC bond-forming reactions such as hydrogenolysis, olefin insertion, arylboronic coupling, etc. The variety of possible combinations offers a powerful tool for the selective synthesis of unusual and not readily accessible aromatics.

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Palladium-Catalyzed C(sp3)-H Arylation of Benzo[b]thiophen-3(2H)-one 1,1-Dioxide

Journal of Chemistry ◽

10.1155/2019/5032325 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7

Author(s):

Hailong Liu ◽

Wenjing Li ◽

Haiyan Fu ◽

Hua Chen ◽

Ruixiang Li ◽

...

Keyword(s):

Catalytic System ◽

Good Yield ◽

Synthesis Route ◽

Palladium Catalyzed

A new concise synthesis route of 2-phenylbenzo[b]thiophen-3(2H)-one 1,1-dioxide from benzo[b]thiophen-3(2H)-one 1,1-dioxide was developed using palladium-catalyzed C(sp3)-H arylation. Compared with the traditional route, this protocol can effectively save many steps and combine with the current research hotspot, C(sp3)-H activation. Moreover, this catalytic system is easy to operate and a good yield can be achieved.

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A dual light-driven palladium catalyst: Breaking the barriers in carbonylation reactions

Science ◽

10.1126/science.aba5901 ◽

2020 ◽

Vol 368 (6488) ◽

pp. 318-323 ◽

Cited By ~ 25

Author(s):

Gerardo M. Torres ◽

Yi Liu ◽

Bruce A. Arndtsen

Keyword(s):

Bond Cleavage ◽

Oxidative Addition ◽

Reductive Elimination ◽

Coupling Reactions ◽

Ambient Conditions ◽

Inherent Limitation ◽

Carbonyl Derivatives ◽

Palladium Catalyzed ◽

Light Excitation ◽

Metal Catalyzed

Transition metal–catalyzed coupling reactions have become one of the most important tools in modern synthesis. However, an inherent limitation to these reactions is the need to balance operations, because the factors that favor bond cleavage via oxidative addition ultimately inhibit bond formation via reductive elimination. Here, we describe an alternative strategy that exploits simple visible-light excitation of palladium to drive both oxidative addition and reductive elimination with low barriers. Palladium-catalyzed carbonylations can thereby proceed under ambient conditions, with challenging aryl or alkyl halides and difficult nucleophiles, and generate valuable carbonyl derivatives such as acid chlorides, esters, amides, or ketones in a now-versatile fashion. Mechanistic studies suggest that concurrent excitation of palladium(0) and palladium(II) intermediates is responsible for this activity.

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Reversible Oxidative-Addition and Reductive-Elimination of Thiophene from a Titanium Complex and Its Thermally-Induced Hydrodesulfurization Chemistry

10.26434/chemrxiv.10321946.v1 ◽

2019 ◽

Author(s):

Alejandra Gomez-Torres ◽

J. Rolando Aguilar-Calderón ◽

Carlos Saucedo ◽

Aldo Jordan ◽

Alejandro J. Metta-Magaña ◽

...

Keyword(s):

Dft Calculations ◽

Ring Opening ◽

Thiophene Ring ◽

Oxidative Addition ◽

Reductive Elimination ◽

Thermally Induced ◽

Titanium Complex

The masked Ti(II) synthon (Ketguan)(η6-ImDippN)Ti (1) oxidatively adds across thiophene to give ring-opened (Ketguan)(ImDippN)Ti[κ2-S(CH)3CH] (2). Complex 2 is photosensitive, and upon exposure to light, reductively eliminates thiophene to regenerate 1 – a rare example of early-metal mediated oxidative-addition/reductive-elimination chemistry. DFT calculations indicate strong titanium π-backdonation to the thiophene π*-orbitals leads to the observed thiophene ring opening across titanium, while a proposed photoinduced LMCT promotes the reverse thiophene elimination from 2. Finally, pressurizing solutions of 2 with H2 (150 psi) at 80 °C leads to the hydrodesulfurization of thiophene to give the Ti(IV) sulfide (Ketguan)(ImDippN)Ti(S) (3) and butane.

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Dual Nickel/Palladium-Catalyzed Reductive Cross-Coupling Reactions Between Two Phenol Derivatives

10.26434/chemrxiv.12448970.v1 ◽

2020 ◽

Author(s):

Baojian Xiong ◽

Yue Li ◽

Yin Wei ◽

Søren Kramer ◽

Zhong Lian

Keyword(s):

Functional Group ◽

Low Cost ◽

Cross Coupling ◽

Coupling Reactions ◽

Phenol Derivatives ◽

Cross Coupling Reactions ◽

Palladium Catalyzed ◽

One Step ◽

Aryl Tosylates ◽

Low Sensitivity

Cross-coupling between substrates that can be easily derived from phenols is highly attractive due to the abundance and low cost of phenols. Here, we report a dual nickel/palladium-catalyzed reductive cross-coupling between aryl tosylates and aryl triflates; both substrates can be accessed in just one step from readily available phenols. The reaction has a broad functional group tolerance and substrate scope (>60 examples). Furthermore, it displays low sensitivity to steric effects demonstrated by the synthesis of a 2,2’disubstituted biaryl and a fully substituted aryl product. The widespread presence of phenols in natural products and pharmaceuticals allow for straightforward late-stage functionalization, illustrated with examples such as Ezetimibe and tyrosine. NMR spectroscopy and DFT calculations indicate that the nickel catalyst is responsible for activating the aryl triflate, while the palladium catalyst preferentially reacts with the aryl tosylate.

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Nickel-Catalyzed Inter- and Intramolecular Carbon-Sulfur Bond Metathesis by Reversible Arylation

10.26434/chemrxiv.8168180.v1 ◽

2019 ◽

Author(s):

Tristan Delcaillau ◽

Alessandro Bismuto ◽

Zhong Lian ◽

Bill Morandi

Keyword(s):

Good Yield ◽

Functional Group ◽

Product Formation ◽

Single Bond ◽

Ring Closing Metathesis ◽

Catalytic Systems ◽

Metathesis Reactions ◽

New Applications ◽

Further Development ◽

Sulfur Bond

A nickel-catalyzed carbon-sulfur bond metathesis has been developed to access high-value thioethers. 1,2-bis(dicyclohexylphosphino)ethane (dcype) is essential to promote this highly functional group tolerant reaction. Further, synthetically challenging macrocycles could be obtained in good yield in an unusual example of ring-closing metathesis which does not involve alkene bonds. In-depth organometallic studies support a reversible Ni(0)-Ni(II) pathway to product formation. Overall, this work does not only disclose a more sustainable and more functional group tolerant alternative to previous catalytic systems based on Pd, but also presents new applications and mechanistic information which are highly relevant to the further development and application of unusual single bond metathesis reactions.

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Differentiation and Functionalization of Adjacent, Remote C–H Bonds

10.26434/chemrxiv.8156561 ◽

2019 ◽

Author(s):

Hang Shi ◽

Lu Yi ◽

Jiang Weng ◽

Katherine Bay ◽

Xiangyang Chen ◽

...

Keyword(s):

Catalytic System ◽

Functional Group ◽

Hydrocinnamic Acid ◽

Molecular Architectures ◽

Site Selective ◽

Developing Strategies

Site-selective functionalizations of C–H bonds will ultimately afford chemists transformative tools for editing and constructing complex molecular architectures1-4. Towards this goal, developing strategies to activate C–H bonds that are distal from a functional group is essential4-6. In this context, distinguishing remote C–H bonds on adjacent carbon atoms is an extraordinary challenge due to the lack of electronic or steric bias between the two positions. Herein, we report the design of a catalytic system leveraging a remote directing template and a transient norbornene mediator to selectively activate a previously inaccessible remote C–H bond that is one bond further away. The generality of this approach has been demonstrated with a range of heterocycles, including a complex anti-leukemia agent, and hydrocinnamic acid substrates.

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Enantioselective alpha-Arylation of Benzamides via Synergistic Nickel and Metallaphotoredox Catalysis

10.26434/chemrxiv.9978824.v1 ◽

2019 ◽

Author(s):

John Montgomery ◽

Alexander W. Rand

Keyword(s):

Catalytic System ◽

Functional Group ◽

Enantiomeric Excess ◽

New Method ◽

Aryl Bromides

A new method to access alpha-arylated benzamides has been enabled by metallaphotoredox catalysis. This system allows for non-directed C–H functionalization of N-alkyl benzamides using a dual nickel/iridium catalytic system to form tertiary stereocenters in good enantiomeric excess and moderate yields. This reaction shows excellent functional group compatibility and can be performed using a number of sterically and electronically different aryl bromides and secondary benzamides.

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