Nickel-Catalyzed Hydroalkenylation of Alkynes through C–F Bond Activation: Synthesis of 2-Fluoro-1,3-dienes

Synthesis ◽  
2017 ◽  
Vol 49 (16) ◽  
pp. 3569-3575 ◽  
Author(s):  
Junji Ichikawa ◽  
Yota Watabe ◽  
Kohei Kanazawa ◽  
Takeshi Fujita
Keyword(s):  
Bond Activation ◽  
Oxidative Cyclization ◽  
Coupling Reactions ◽  
Mechanistic Studies ◽  
Co Catalyst

2-Fluoro-1,3-dienes were synthesized through nickel-catalyzed coupling reactions between β,β-difluorostyrenes and alkynes in the presence of ZrF4 as co-catalyst and a hydride source derived from triethylborane and lithium isopropoxide. Mechanistic studies revealed that the carbon–fluorine bond was cleaved by β-fluorine elimination from intermediary nickelacyclopentenes generated through oxidative cyclization of the two substrates.

Cross-Coupling Reactions with 2-Amino-/Acetylamino-Substituted 3-Iodo-1,4-naphthoquinones: Convenient Synthesis of Novel Alkenyl- and Alkynylnaphthoquinones and Derivatives

Synthesis ◽  
2021 ◽  
Author(s):  
Felipe C. Demidoff ◽  
Leandro L. de Carvalho ◽  
Eduardo José P. Rodrigues Filho ◽  
Andréa Luzia F. de Souza ◽  
Chaquip D. Netto
Keyword(s):  
Click Chemistry ◽  
Organic Synthesis ◽  
Biological Activities ◽  
Cross Coupling ◽  
Coupling Reactions ◽  
Large Array ◽  
Terminal Alkyne ◽  
Co Catalyst ◽  
Cross Coupling Reactions ◽  
Convenient Synthesis

AbstractFunctionalized 1,4-naphthoquinones have been employed as versatile synthons in organic synthesis, in addition to presenting a large array of biological activities. Herein, the applications of 2-amino-/ acetylamino-substituted 3-iodo-1,4-naphthoquinones in cross-coupling reactions are described to successfully afford sixteen novel 3-styryl-1,4-naphthoquinones (amino-stilbene-quinone hybrids) and four 3-alkynyl-1,4-naphthoquinone in overall good yields. Interestingly, the alkynylated derivatives could be obtained from ligand- and Pd-free CuI-mediated cross-coupling reactions, after extensive investigations to exclude Pd as a co-catalyst. Lastly, the desilanized terminal alkyne was subjected to click chemistry reactions to give two novel triazole-1,4-naphthoquinone hybrids.

scholarly journals Total syntheses of all tri-oxygenated 16-phytoprostane classes via a common precursor constructed by oxidative cyclization and alkyl–alkyl coupling reactions as the key steps

2017 ◽  
Vol 15 (44) ◽  
pp. 9408-9414 ◽  
Author(s):  
Jakub Smrček ◽  
Radek Pohl ◽  
Ullrich Jahn
Keyword(s):  
Total Synthesis ◽  
Oxidative Cyclization ◽  
Coupling Reactions ◽  
Total Syntheses ◽  
Common Precursor ◽  
Key Steps

A parallel total synthesis of 16-F1t-, 16-E1-phytoprostanes and a first synthesis of 16-D1t-phytoprostanes based on a common precursor are described.

scholarly journals Heterobiaryl synthesis by contractive C–C coupling via P(V) intermediates

Science ◽  
2018 ◽  
Vol 362 (6416) ◽  
pp. 799-804 ◽  
Author(s):  
Michael C. Hilton ◽  
Xuan Zhang ◽  
Benjamin T. Boyle ◽  
Juan V. Alegre-Requena ◽  
Robert S. Paton ◽  
...  
Keyword(s):  
Cross Coupling ◽  
The Other ◽  
Coupling Reactions ◽  
Mechanistic Studies ◽  
Alternative Approach ◽  
Metal Catalyzed ◽  
Polar Functional Groups ◽  
Pharmacological Function ◽  
Complex Drug ◽  
Acidic Alcohol

Heterobiaryls composed of pyridine and diazine rings are key components of pharmaceuticals and are often central to pharmacological function. We present an alternative approach to metal-catalyzed cross-coupling to make heterobiaryls using contractive phosphorus C–C couplings, also termed phosphorus ligand coupling reactions. The process starts by regioselective phosphorus substitution of the C–H bonds para to nitrogen in two successive heterocycles; ligand coupling is then triggered via acidic alcohol solutions to form the heterobiaryl bond. Mechanistic studies imply that ligand coupling is an asynchronous process involving migration of one heterocycle to the ipso position of the other around a central pentacoordinate P(V) atom. The strategy can be applied to complex drug-like molecules containing multiple reactive sites and polar functional groups, and also enables convergent coupling of drug fragments and late-stage heteroarylation of pharmaceuticals.

scholarly journals DFT Study of Unstrained Ketone C-C Bond Activation via Rhodium(I)-Catalyzed Suzuki-Miyaura Cross-Coupling Reactions

2019 ◽  
Author(s):  
Dengmengfei Xiao ◽  
Lili Zhao ◽  
Diego Andrada
Keyword(s):  
Density Functional ◽  
Bond Activation ◽  
Chemical Reactivity ◽  
Cross Coupling ◽  
Underlying Mechanism ◽  
Reductive Elimination ◽  
Coupling Reactions ◽  
Co Catalysts ◽  
Cross Coupling Reactions ◽  
Strain Model

Unstrained cyclic ketones can participate in cooperative Suzuki-Miyaura cross-coupling type reaction using rhodium(I)-based catalyst via C-C bond activation. The regioselectivity indicates a trend where the most substituted side is activated and it is controlled by the beta-substituents. In this work, Density Functional Theory (DFT) calculations have been carried out to disclose the underlying mechanism in the reaction of a ketone series and arylboronate using ylidene as ancillary ligand and pyridine as co-catalysts. The computed energies suggest the reductive elimination step with the highest energy while the reductive elimination has the highest energy barrier. By the means of the Activation Strain Model (ASM) of chemical reactivity, it is found that the ketone strain energy released on the oxidative addition does not control the relativity of the OA reactivity, but indeed is the interaction energy between Rh(I) and C-C bond the ruling effect. The effect of the beta-substituents on regioselectivity has been additionally studied.

scholarly journals Palladium-catalyzed Suzuki-Miyaura coupling of thioureas or thioamides

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Shaoyu Mai ◽  
Wendong Li ◽  
Xue Li ◽  
Yingwei Zhao ◽  
Qiuling Song
Keyword(s):  
Silver Salt ◽  
Coupling Reaction ◽  
Coupling Reactions ◽  
Mechanistic Studies ◽  
Aromatic Rings ◽  
Cross Coupling Reactions ◽  
Broad Array ◽  
Palladium Catalyzed

AbstractCross-coupling reactions involving metal carbene intermediates play an increasingly important role in C–C bond formation. Expanding the carbene precursors to a broader range of starting materials and more diverse products is an ongoing challenge in synthetic organic chemistry. Herein, we report a Suzuki-Miyaura coupling reaction of in situ-generated Pd–carbene complexes via desulfurization of thioureas or thioamides. This strategy enables the preparation of a broad array of substituted amidinium salts and unsymmetrical diaryl ketones. The reaction is readily scalable, compatible with bromo groups on aromatic rings, tolerant to moisture and air and has a broad substrate scope. Furthermore, a single crystal structure of Pd-diaminocarbene complex is obtained and proven to be the key intermediate in both catalytic and stoichiometric reactions. Preliminary mechanistic studies demonstrate the dual role of the silver salt as a desulfurating reagent assisting the elimination of sulfur and as oxidant facilitating the PdII/Pd0/PdII catalytic cycle.

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