Regioselective Synthesis of 2,5-Disubstituted Pyrroles via Stepwise Iododesilylation and Coupling Reactions

2018 ◽  
Vol 71 (3) ◽  
pp. 95 ◽  
Author(s):  
Qixin Yu ◽  
Xiaoyu Li ◽  
Xinyue Wang ◽  
Jianhui Liu
Keyword(s):  
Pyrrole Ring ◽  
Coupling Reaction ◽  
Regioselective Synthesis ◽  
Coupling Reactions ◽  
Pyrrole Derivatives ◽  
Final Choice ◽  
Tetrabutylammonium Fluoride ◽  
Pyrrole Nitrogen

A new protocol has been developed for the regioselective preparation of 2,5-disubstituted pyrroles. This approach is based on a stepwise iododesilylation and a subsequent coupling reaction, involving a 6-step pathway starting from the simplest pyrrole. A variety of 2,5-disubstituted pyrrole derivatives are accessible in moderate to good yields. In this study, the protection group for the pyrrole nitrogen is carefully chosen and N,N-dimethylaminosulfonyl is the final choice, which facilitates the subsequent double lithiation and makes the pyrrole moiety more stable. However, the attempted removal of this group fails under several different conditions. Instead, unexpected dimethylaminosulfonyl migration to the β-position of the pyrrole ring in the presence of tetrabutylammonium fluoride is observed.

An Iron-Based Catalyst Enables The Enantioconvergent Synthesis of Chiral 1,1-Diarylalkanes Through a Suzuki-Miyaura Cross-Coupling Reaction

2020 ◽  
Author(s):  
Chet Tyrol ◽  
Nang Yone ◽  
Connor Gallin ◽  
Jeffery Byers
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Radical Intermediates ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Centered Radical ◽  
Iron Based ◽  
High Yields

By using an iron-based catalyst, access to enantioenriched 1,1-diarylakanes was enabled through an enantioselective Suzuki-Miyaura crosscoupling reaction. The combination of a chiral cyanobis(oxazoline) ligand framework and 1,3,5-trimethoxybenzene additive were essential to afford high yields and enantioselectivities in cross-coupling reactions between unactivated aryl boronic esters and a variety of benzylic chlorides, including challenging ortho-substituted benzylic chloride substrates. Mechanistic investigations implicate a stereoconvergent pathway involving carbon-centered radical intermediates.

An Unprecedented Cyano-Induced Sodium Nitrite-Catalyzed C(sp3)-H and C(sp2)-H Coupling Reaction

2018 ◽  
Vol 15 (7) ◽  
pp. 989-994 ◽  
Author(s):  
Ling Li ◽  
Bo Su ◽  
Yuxiu Liu ◽  
Qingmin Wang
Keyword(s):  
Sodium Nitrite ◽  
Oxidative Coupling ◽  
High Resolution Mass Spectrometry ◽  
Coupling Reaction ◽  
13C Nmr Spectroscopy ◽  
Coupling Reactions ◽  
Reaction Conditions ◽  
1H And 13C Nmr ◽  
Oxidative Coupling Reaction ◽  
Oxidative Coupling Reactions

Aim and Objective: During the investigation of sodium nitrite-catalyzed oxidative coupling reaction of aryls, an unprecedented C(sp2)-H and C(sp3)-H coupling of substituted 2-aryl acetonitrile was found. Materials and Methods: The structure of the coupled product was confirmed by 1H and 13C NMR spectroscopy and high-resolution mass spectrometry (HRMS), and comparison of its derivatives with known compounds. The effects of methoxy group in the benzene ring on the reaction were evaluated. Results: The optimized reaction conditions are summarized as follows: CF3SO3H/substrate = 1.5 equiv., NaNO2/substrate = 0.3 equiv., CH3CN as solvent. 2-(4-Methoxyphenyl)acetonitrile and 2-(3,4,5- trimethoxyphenyl)acetonitrile could also generate C(sp2)-H and C(sp3)-H coupling. The coupling reaction occurred as a typical radial mechanism. Conclusion: An unprecedented cyano-induced, NaNO2-catalyzed oxidative C(sp3)-H and C(sp2)-H coupling was reported. The reaction proceeded under very mild conditions, using O2 in the air as terminal oxidant. The unique oxidative manner might provide more inspiration for the development of intriguing oxidative coupling reactions.

Catch It If You Can: Copper-Catalyzed (Transfer) Hydrogenation Reactions and Coupling Reactions by Intercepting Reactive Intermediates Thereof

Synthesis ◽  
2020 ◽  
Vol 52 (17) ◽  
pp. 2483-2496
Author(s):  
Johannes F. Teichert ◽  
Lea T. Brechmann
Keyword(s):  
Coupling Reaction ◽  
Reactive Intermediates ◽  
Transfer Hydrogenation ◽  
Coupling Reactions ◽  
Bond Forming ◽  
Starting Point ◽  
Bond Forming Reactions ◽  
Hydrogenation Reactions ◽  
Multicomponent Coupling Reactions ◽  
Trapping Reactions

The key reactive intermediate of copper(I)-catalyzed alkyne semihydrogenations is a vinylcopper(I) complex. This intermediate can be exploited as a starting point for a variety of trapping reactions. In this manner, an alkyne semihydrogenation can be turned into a dihydrogen­-mediated coupling reaction. Therefore, the development of copper-catalyzed (transfer) hydrogenation reactions is closely intertwined with the corresponding reductive trapping reactions. This short review highlights and conceptualizes the results in this area so far, with H2-mediated carbon–carbon and carbon–heteroatom bond-forming reactions emerging under both a transfer hydrogenation setting as well as with the direct use of H2. In all cases, highly selective catalysts are required that give rise to atom-economic multicomponent coupling reactions with rapidly rising molecular complexity. The coupling reactions are put into perspective by presenting the corresponding (transfer) hydrogenation processes first.1 Introduction: H2-Mediated C–C Bond-Forming Reactions2 Accessing Copper(I) Hydride Complexes as Key Reagents for Coupling Reactions; Requirements for Successful Trapping Reactions 3 Homogeneous Copper-Catalyzed Transfer Hydrogenations4 Trapping of Reactive Intermediates of Alkyne Transfer Semi­hydrogenation Reactions: First Steps Towards Hydrogenative Alkyne Functionalizations 5 Copper(I)-Catalyzed Alkyne Semihydrogenations6 Copper(I)-Catalyzed H2-Mediated Alkyne Functionalizations; Trapping of Reactive Intermediates from Catalytic Hydrogenations6.1 A Detour: Copper(I)-Catalyzed Allylic Reductions, Catalytic Generation of Hydride Nucleophiles from H2 6.2 Trapping with Allylic Electrophiles: A Copper(I)-Catalyzed Hydro­allylation Reaction of Alkynes 6.3 Trapping with Aryl Iodides7 Conclusion

Selectfluor-induced C(sp2)–O coupling reaction of N-substituted anilines with hydroxylamine derivatives

2018 ◽  
Vol 16 (33) ◽  
pp. 6017-6024 ◽  
Author(s):  
Bin Sun ◽  
Shi Yin ◽  
Xiaohui Zhuang ◽  
Can Jin ◽  
Weike Su
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Substituted Anilines ◽  
Metal Free ◽  
Cross Coupling Reactions ◽  
Hydroxylamine Derivatives

We developed a novel metal-free method for the construction of C(sp2)–O bonds via oxidative cross-coupling reactions between various N-substituted anilines and hydroxylamine derivatives just using commercially available Selectfluor as an oxidant.

Room-Temperature, Water-Promoted, Radical-Coupling Reactions of Phenols with tert-Butyl Nitrite

Synlett ◽  
2017 ◽  
Vol 28 (16) ◽  
pp. 2153-2156 ◽  
Author(s):  
Wen-Ting Wei ◽  
Hongze Liang ◽  
Wen-Ming Zhu ◽  
Weida Liang ◽  
Yi Wu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Phenol Derivative ◽  
Tert Butyl ◽  
Radical Coupling ◽  
Air Atmosphere ◽  
Cross Coupling Reaction ◽  
Temperature Water

A radical–radical cross-coupling reaction of phenols with tert-butyl nitrite has been developed with the use of water as an additive. This method allows the construction of C–N bonds under an air atmosphere at room temperature, providing the ortho-nitrated phenol derivative in moderate to good yields.

scholarly journals Efficient in situ N-heterocyclic carbene palladium(ii) generated from Pd(OAc)2 catalysts for carbonylative Suzuki coupling reactions of arylboronic acids with 2-bromopyridine under inert conditions leading to unsymmetrical arylpyridine ketones: synthesis, characterization and cytotoxic activities

RSC Advances ◽  
2018 ◽  
Vol 8 (70) ◽  
pp. 40000-40015 ◽  
Author(s):  
Nedra Touj ◽  
Abdullah S. Al-Ayed ◽  
Mathieu Sauthier ◽  
Lamjed Mansour ◽  
Abdel Halim Harrath ◽  
...  
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Suzuki Coupling ◽  
Boronic Acids ◽  
Cytotoxic Activities ◽  
Coupling Reactions ◽  
Component System ◽  
Arylboronic Acids ◽  
Cross Coupling Reaction

The in situ prepared four component system Pd(OAc)2, 1,3-dialkylbenzimidazolium halides 2a–i and 4a–i, K2CO3 under CO atmosphere catalyses carbonylative cross-coupling reaction of 2-bromopyridine with various boronic acids to yield unsymmetrical arylpyridine ketones.

An easily prepared palladium-hydrogel nanocomposite catalyst for C–C coupling reactions

2014 ◽  
Vol 2 (44) ◽  
pp. 18952-18958 ◽  
Author(s):  
Mitasree Maity ◽  
Uday Maitra
Keyword(s):  
Palladium Nanoparticles ◽  
Room Temperature ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Sodium Cyanoborohydride ◽  
Efficient Catalyst ◽  
Suzuki Coupling Reaction ◽  
Reaction In Water ◽  
Hydrogel Nanocomposite

Palladium nanoparticles were efficiently prepared in situ by sodium cyanoborohydride reduction of Pd(ii) at room temperature using calcium-cholate hydrogel fibers as templates. The PdNPs self-organize on the gel fibers, which supports the controlled growth as well as stabilization of PdNPs. The hybrid xerogel was used as an efficient catalyst for the Suzuki coupling reaction in water.

scholarly journals Synthesis of 9-arylalkynyl- and 9-aryl-substituted benzo[b]quinolizinium derivatives by Palladium-mediated cross-coupling reactions

2018 ◽  
Vol 14 ◽  
pp. 1871-1884 ◽  
Author(s):  
Siva Sankar Murthy Bandaru ◽  
Darinka Dzubiel ◽  
Heiko Ihmels ◽  
Mohebodin Karbasiyoun ◽  
Mohamed M A Mahmoud ◽  
...  
Keyword(s):  
Emission Intensity ◽  
Binding Constants ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Sonogashira Coupling ◽  
Reaction Conditions ◽  
Quadruplex Dna ◽  
Cross Coupling Reactions ◽  
Sonogashira Coupling Reaction

9-Arylbenzo[b]quinolizinium derivatives were prepared with base-free Suzuki–Miyaura coupling reactions between benzo[b]quinolizinium-9-trifluoroborate and selected benzenediazonium salts. In addition, the Sonogashira coupling reaction between 9-iodobenzo[b]quinolizinium and the arylalkyne derivatives yielded four novel 9-(arylethynyl)benzo[b]quinolizinium derivatives under relatively mild reaction conditions. The 9-(N,N-dimethylaminophenylethynyl)benzo[b]quinolizinium is only very weakly emitting, but the emission intensity increases by a factor >200 upon protonation, so that this derivative may operate as pH-sensitive light-up probe. Photometric and fluorimetric titrations of duplex and quadruplex DNA to 9-(arylethynyl)benzo[b]quinolizinium derivatives revealed a significant binding affinity of these compounds towards both DNA forms with binding constants ofKb= 0.2–2.2 × 105M−1.

The Synthesis of Pharmaceuticals: The Effective Application of Secondary Boronic Esters in Enantioselective Suzuki ‐ Miyaura Cross ‐ Coupling Reactions

2016 ◽  
Author(s):  
Jonathon Moir
Keyword(s):  
Natural Products ◽  
Human Life ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Boronic Esters ◽  
Carbon Carbon Bonds ◽  
Effective Drugs

Pharmaceuticals and drugs have become an indispensable part of human life. Presently, a myriad of different drugs are available for a variety of mental and physical health concersn. The synthesis of these drugs, however, remains an elusive and often difficult aspect of the industry. The importance of chirality, or "handedness", in the synthesis of natural products is paramount, as any given pair of enantiomers can have widely differing physiological effects. As such, the ability to control the enantioselectivity of a reaction is of the utmost importance. One example of a facile method used to form carbon-carbon bonds is the Suzuki-Miyaura cross-coupling reaction. Not only is this reaction effective at coupling primary organoboronic esters with organohalides, but recent work in the Crudden group in the Department of Chemistry has revealed an effective method of also cross-couplingchiral secondary organoboronic esters with good retention of stereochemistry. This work, the first of its kind, is crucial in developing single-handed natural products for a wide array of applications, including applications in the pharmaceutical industry. The end result is safer and more effective drugs for distribution to the general public. To expand the scope of this project, new substrates are currently being synthesized for cross-coupling applications. The overall goal is to improve upon current methodologies, while helping to meet the industrial and academic needs of the future.  

Regiospecific Palladium-Catalyzed Cross-Coupling Reactions Using the Operational Equivalent of 1,3-Dilithiopropyne

Synthesis ◽  
2020 ◽  
Vol 52 (16) ◽  
pp. 2387-2394 ◽  
Author(s):  
Jorge A. Cabezas ◽  
Natasha Ferllini
Keyword(s):  
Coupling Reaction ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Terminal Alkyne ◽  
Copper Iodide ◽  
Reaction Conditions ◽  
Cross Coupling Reactions ◽  
Cross Coupling Reaction ◽  
Palladium Catalyzed ◽  
High Yields

A regiospecific palladium-catalyzed cross-coupling reaction using the operational equivalent of the dianion 1,3-dilithiopropyne, with aromatic iodides is reported. This reaction gives high yields of 1-propyn-1-yl-benzenes and 2-(propyn-1-yl)thiophenes in the presence of catalytic amounts of palladium(0) or (II) and stoichiometric amounts of copper iodide. No terminal alkyne or allene isomers were detected. Reaction conditions were very mild and several functional groups were tolerated.

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