scholarly journals Cu/Pd-catalyzed borocarbonylative trifunctionalization of alkynes and allenes: synthesis of β-geminal-diboryl ketones

2021 ◽  
Author(s):  
Yang Yuan ◽  
Fu-Peng Wu ◽  
Anke Spannenberg ◽  
Xiao-Feng Wu
Keyword(s):  
Organic Synthesis ◽  
Functional Group ◽  
Building Blocks ◽  
Mechanistic Studies ◽  
Efficient Strategy ◽  
New Class ◽  
Reaction Proceeds

AbstractFunctionalized bisboryl compounds have recently emerged as a new class of synthetically useful building blocks in organic synthesis. Herein, we report an efficient strategy to synthesize β-geminal-diboryl ketones enabled by a Cu/Pd-catalyzed borocarbonylative trifunctionalization of readily available alkynes and allenes. This reaction promises to be a useful method for the synthesis of functionalized β-geminal-diboryl ketones with broad functional group tolerance. Mechanistic studies suggest that the reaction proceeds through borocarbonylation/hydroboration cascade of both alkynes and allenes.

Cascade CuH-Catalyzed Conversion of Alkynes to Enantioenriched 1,1-Disubstituted Products

2019 ◽  
Author(s):  
De-Wei Gao ◽  
Yang Gao ◽  
Huiling Shao ◽  
Tian-Zhang Qiao ◽  
Xin Wang ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Medicinal Chemistry ◽  
Proteasome Inhibitors ◽  
Building Blocks ◽  
Unique Role ◽  
Efficient Strategy ◽  
Carbon Centers ◽  
Rapid Access ◽  
Cascade Catalysis ◽  
Privileged Scaffolds

Enantioenriched <i>α</i>-aminoboronic acids play a unique role in medicinal chemistry and have emerged as privileged pharmacophores in proteasome inhibitors. Additionally, they represent synthetically useful chiral building blocks in organic synthesis. Recently, CuH-catalyzed asymmetric alkene hydrofunctionalization has become a powerful tool to construct stereogenic carbon centers. In contrast, applying CuH cascade catalysis to achieve reductive 1,1-difunctionalization of alkynes remains an important, but largely unaddressed, synthetic challenge. Herein, we report an efficient strategy to synthesize <i>α</i>-aminoboronates <i>via </i>CuH-catalyzed hydroboration/hydroamination cascade of readily available alkynes. Notably, this transformation selectively delivers the desired 1,1-heterodifunctionalized product in favor of alternative homodifunctionalized, 1,2-heterodifunctionalized, or reductively monofunctionalized byproducts, thereby offering rapid access to these privileged scaffolds with high chemo-, regio- and enantioselectivity.<br>

Bromotrifluoromethane: A Useful Reagent for Hydrotrifluoromethylation of Alkenes and Alkynes

Synlett ◽  
2018 ◽  
Vol 29 (08) ◽  
pp. 1028-1032 ◽  
Author(s):  
Xing Zheng ◽  
Xingang Zhang ◽  
Yu-Yan Ren
Keyword(s):  
Visible Light ◽  
Organic Synthesis ◽  
Functional Group ◽  
Mild Conditions ◽  
Industrial Material ◽  
Reaction Proceeds

Bromotrifluoromethane (CF3Br) is a simple, inexpensive and abundant industrial material employed as a trifluoromethylating reagent. However, only limited strategies using CF3Br as a fluorine source are reported. Herein, we describe a visible-light-induced hydrotrifluoromethylation of alkenes and alkynes with CF3Br. The reaction proceeds under mild conditions with good functional group tolerance, providing a new route for the application of BrCF3 in organic synthesis.

scholarly journals Intermolecular 3+3 Ring Expansion of Aziridines to Dehydropiperidines through the Intermediacy of Aziridinium Ylides

2019 ◽  
Author(s):  
Jennifer Schomaker ◽  
Josephine Eshon ◽  
Kate A. Nicastri ◽  
Steven C. Schmid ◽  
William T. Raskopf ◽  
...  
Keyword(s):  
Natural Product ◽  
Functional Group ◽  
Ring Expansion ◽  
Sigmatropic Rearrangement ◽  
Reactive Intermediate ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Complex Molecules ◽  
Form Complex ◽  
Reaction Proceeds

Bicyclic aziridines undergo formal [3+3] ring expansion reactions when exposed to rhodium-bound vinyl carbenes to form complex dehydropiperidines in a highly stereocontrolled rearrangement. Mechanistic studies and DFT computations indicate the reaction proceeds through the formation of a vinyl aziridinium ylide; this reactive intermediate undergoes a concerted, asynchronous, pseudo-[1,4]- sigmatropic rearrangement to directly furnish the heterocyclic products with net retention at the new C-C bond. In combination with an asymmetric silver-catalyzed aziridination developed in our group, this method quickly delivers enantioenriched scaffolds with up to three contiguous stereocenters. The mild reaction conditions, functional group tolerance, and high stereochemical retention of this method are especially well-suited for appending piperidine motifs to natural product and complex molecules. Ultimately, our work establishes the value of underutilized aziridinium ylides as key intermediates in strategies to convert small, strained rings to larger N-heterocycles.

scholarly journals Cobalt-catalyzed deoxygenative triborylation of allylic ethers to access 1,1,3-triborylalkanes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei Jie Teo ◽  
Xiaoxu Yang ◽  
Yeng Yeng Poon ◽  
Shaozhong Ge
Keyword(s):  
Building Blocks ◽  
Mechanistic Studies ◽  
Deuterium Labeling ◽  
Bond Forming ◽  
Carbon Carbon Bond ◽  
Synthetic Utility ◽  
Reaction Proceeds ◽  
Site Selective ◽  
And Control ◽  
Allylic Ethers

Abstract Polyborylated organic compounds have been emerging as versatile building blocks in chemical synthesis. Here we report a selective cobalt-catalyzed deoxygenative 1,1,3-triborylation reaction of allylic ethers with pinacolborane to prepare 1,1,3-triborylalkane compounds. With naturally abundant and/or synthetic cinnamic methyl ethers as starting materials, we have achieved the synthesis of a variety of 1,1,3-triborylalkanes (25 examples). The synthetic utility of these 1,1,3-triborylalkanes is demonstrated through site-selective allylation, protodeborylation, and consecutive carbon-carbon bond-forming reactions. Mechanistic studies including deuterium-labeling and control experiments suggest that this 1,1,3-triborylation reaction proceeds through initial cobalt-catalyzed deoxygenative borylation of allylic ethers to form allylic boronates followed by cobalt-catalyzed 1,1-diborylation of the resulting allylic boronates.

scholarly journals Palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides

2017 ◽  
Vol 13 ◽  
pp. 2610-2616 ◽  
Author(s):  
Tao Fan ◽  
Wei-Dong Meng ◽  
Xingang Zhang
Keyword(s):  
Alkyl Radical ◽  
Functional Group ◽  
High Efficiency ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
Type Reaction ◽  
Alkyl Bromides ◽  
Reaction Proceeds ◽  
Palladium Catalyzed ◽  
Hydroxy Groups

An efficient palladium-catalyzed Heck-type reaction of secondary trifluoromethylated alkyl bromides has been developed. The reaction proceeds under mild reaction conditions with high efficiency and excellent functional group tolerance, even towards formyl and hydroxy groups. Preliminary mechanistic studies reveal that a secondary trifluoromethylated alkyl radical is involved in the reaction.

scholarly journals Exploring endoperoxides as a new entry for the synthesis of branched azasugars

2017 ◽  
Vol 13 ◽  
pp. 644-647 ◽  
Author(s):  
Svenja Domeyer ◽  
Mark Bjerregaard ◽  
Henrik Johansson ◽  
Daniel Sejer Pedersen
Keyword(s):  
Singlet Oxygen ◽  
Organic Synthesis ◽  
Building Blocks ◽  
New Class ◽  
Potential Use ◽  
New Entry

A new class of nitrogen-containing endoperoxides were synthesised by a photochemical [4 + 2]-cycloaddition between a diene and singlet oxygen. The endoperoxides were dihydroxylated and protected to provide a series of endoperoxide building blocks for organic synthesis, with potential use as precursors for the synthesis of branched azasugars. Preliminary exploration of the chemistry of these building blocks provided access to a variety of derivatives including tetrahydrofurans, epoxides and protected amino-tetraols.

scholarly journals One-Pot Reductive Acetylation of Aldehydes using 1-Hydrosilatrane in Acetic Acid

SynOpen ◽  
2019 ◽  
Vol 03 (01) ◽  
pp. 1-3 ◽  
Author(s):  
Reuben James ◽  
Sharon Herlugson ◽  
Sami Varjosaari ◽  
Vladislav Skrypai ◽  
Zainab Shakeel ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Organic Synthesis ◽  
Functional Group ◽  
Building Blocks ◽  
Flash Chromatography ◽  
Primary Alcohols ◽  
Facile Synthesis ◽  
One Pot ◽  
Aryl Aldehydes ◽  
Mild Conditions

A one-pot, direct reductive acetylation of aldehydes was achieved under mild conditions using 1-hydrosilatrane as a safe and easily accessible catalyst. Described herein is a facile synthesis that produces acylated primary alcohols that can serve as valuable building blocks for organic synthesis. The method has good functional group tolerance and works for a range of aryl aldehydes, with the notable exception of electron-rich arenes. A library of esters was isolated by flash chromatography in yields as high as 92%.

scholarly journals Integrating Allyl Electrophiles into Nickel-Catalyzed Conjunctive Cross-Coupling

2019 ◽  
Author(s):  
Van Tran ◽  
Zi-Qi Li ◽  
Timothy Gallagher ◽  
Joseph Derosa ◽  
Peng Liu ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Cross Coupling ◽  
Building Blocks ◽  
Reductive Elimination ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Wide Range ◽  
Directing Group ◽  
Weakly Coordinating ◽  
Analogous Method

Allylation and conjunctive cross-coupling represent two useful, yet largely distinct, reactivity paradigms in catalysis. The union of these two processes would offer exciting possibilities in organic synthesis but remains largely unknown. Herein, we report the use of allyl electrophiles in nickel-catalyzed conjunctive cross-coupling with a non-conjugated alkene and dimethylzinc. The transformation is enabled by weakly coordinating, monodentate azaheterocycle directing groups, that useful building blocks in synthesis, including saccharin, pyridones, pyrazoles, and triazoles. The reaction occurs under mild conditions and is compatible with a wide range of allyl electrophiles. High chemoselectivity through substrate directivity is demonstrated in the facile reactivity of the β-γ alkene of the starting material, while the ε-ζ alkene of the product is preserved. The generality of this approach is further illustrated through the development of analogous method with alkyne substrates. Mechanistic studies reveal the importance of the weakly coordinating directing group in dissociating to allow binding of the allyl moiety to facilitate C(sp<sup>3</sup>)–C(sp<sup>3</sup>) reductive elimination.

Recent Advances in the Sustainable Synthesis of Quinazolines Using Earth-Abundant First Row Transition Metals

2020 ◽  
Vol 24 (15) ◽  
pp. 1775-1792 ◽  
Author(s):  
Sumera Zaib ◽  
Imtiaz Khan
Keyword(s):  
Transition Metals ◽  
Organic Synthesis ◽  
Molecular Diversity ◽  
Functional Group ◽  
Transition Metal Catalysts ◽  
Mechanistic Studies ◽  
Pharmacological Activities ◽  
Modular Assembly ◽  
Diverse Range ◽  
Earth Abundant

Achieving challenging molecular diversity in contemporary chemical synthesis remains a formidable hurdle, particularly in the delivery of diversified bioactive heterocyclic pharmacophores for drug design and pharmaceutical applications. The coupling methods that combine a diverse range of readily accessible and commercially available pools of substrates under the action of earth-abundant first row transition metal catalysts have certainly matured into powerful tools, thus offering sustainable alternatives to revolutionize the organic synthesis. This minireview highlights the successful utilization of the catalytic ability of the first row transition metals (Mn, Fe, Ni, Cu) in the modular assembly of quinazoline heterocycle, ubiquitously present in numerous alkaloids, commercial medicines and is associated with a diverse range of pharmacological activities. The broad substrate scope and high functional group tolerance of the targeted methods were extensively explored, identifying the future strategic advances in the field. The investigation will also be exemplified with mechanistic studies as long as they are deemed necessary.

Acetic Acid-Promoted Rhodium(III)-Catalyzed Hydroarylation of Terminal Alkynes

Synlett ◽  
2019 ◽  
Vol 30 (08) ◽  
pp. 932-938 ◽  
Author(s):  
Chang-Lin Duan ◽  
Xing-Yu Liu ◽  
Yun-Xuan Tan ◽  
Rui Ding ◽  
Shiping Yang ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Functional Group ◽  
Bond Activation ◽  
Side Reactions ◽  
Terminal Alkynes ◽  
Terminal Alkyne ◽  
Mechanistic Studies ◽  
Mild Conditions ◽  
Reaction Proceeds

Rhodium(III)-catalyzed hydroarylation of terminal alkynes has not previously been achieved because of the inevitable oligomerization and other side reactions. Here, we report a novel Cp*Rh(III)-catalyzed hydroarylation of terminal alkynes in acetic acid as solvent to facilitate the C–H bond activation and subsequent transformations. This reaction proceeds under mild conditions, providing an effective approach to the synthesis of alkenylated heterocycles in high to excellent yields (31–99%) with a broad substrate scope (37 examples) and good functional-group compatibility. In this transformation, the loading of the alkyne can be reduced to 1.2 equivalents, which indicates the significant role of HOAc in lowering the reaction temperature and suppressing the oligomerization of the terminal alkyne. Preliminary mechanistic studies are also presented.

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