Metal-free [3+3] benzannulation of 1-indanylidene-malononitrile with Morita–Baylis–Hillman carbonates: direct access to functionalized fluorene and fluorenone derivatives

2020 ◽  
Vol 56 (13) ◽  
pp. 1948-1951 ◽  
Author(s):  
Ya-Sa Xie ◽  
Run-Feng Huang ◽  
Ran Li ◽  
Chuan-Bao Zhang ◽  
Ji-Ya Fu ◽  
...  
Keyword(s):  
Direct Access ◽  
Metal Free ◽  
Wide Range ◽  
High Yields

An efficient [3+3] benzannulation of Morita–Baylis–Hillman carbonates with 1-indanylidenemalononitrile was achieved selectively delivering a wide range of functional fluorene or fluorenone compounds in high yields (up to 86% yields).

scholarly journals Direct access to multi-functionalized benzenes via [4 + 2] annulation of α-cyano-β-methylenones and α,β-unsaturated aldehydes

RSC Advances ◽  
2020 ◽  
Vol 10 (49) ◽  
pp. 29171-29174 ◽  
Author(s):  
Qianfa Jia ◽  
Yunfei Lan ◽  
Xin Ye ◽  
Yinhe Lin ◽  
Qiao Ren
Keyword(s):  
Direct Access ◽  
Reaction Conditions ◽  
Metal Free ◽  
Unsaturated Aldehydes ◽  
Wide Range ◽  
High Yields

An efficient [4 + 2] benzannulation of α-cyano-β-methylenones and α,β-unsaturated aldehydes was achieved under metal-free reaction conditions selectively delivering a wide range of polyfunctional benzenes in high yields respectively (up to 94% yield).

Iodide-Catalyzed Carbonylation–Benzylation of Benzyl Chlorides with Potassium Aryltrifluoroborates under Ambient Pressure of Carbon Monoxide

Synlett ◽  
2017 ◽  
Vol 29 (03) ◽  
pp. 369-374 ◽  
Author(s):  
Wei Han ◽  
Junjie Chen ◽  
Fengli Jin ◽  
Xiaorong Yuan
Keyword(s):  
Carbon Monoxide ◽  
Ambient Pressure ◽  
The Novel ◽  
Metal Free ◽  
Benzyl Chlorides ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Novel Method ◽  
High Yields ◽  
Co Gas

Tetra-N-butylammonium iodide (TBAI) catalyzed carbonylation–benzylation of unactivated benzyl chlorides with potassium aryltrifluoroborates using CO gas has been developed. This reaction is transition-metal free, is carried out under ambient pressure, and provides a wide range of 1,2,3-triarylpropan-1-one derivatives in high yields. The novel method represents a significant improvement over the traditional palladium-catalyzed carbonylation.

An Exploration of Organocatalyst 1,4-Diazabicyclo[2.2.2]octane in the Direct Regioselective and Chemoselective γ-Addition of β-Keto Amide on Isatin to Afford Structurally Diverse Molecular Frameworks

2015 ◽  
Vol 68 (3) ◽  
pp. 453 ◽  
Author(s):  
Pramod B. Thakur ◽  
Harshadas M. Meshram
Keyword(s):  
Environmentally Benign ◽  
Direct Access ◽  
Metal Free ◽  
Structural Framework ◽  
High Yields

An efficient protocol promoted by 1,4‐diazabicyclo[2.2.2]octane is described for the regioselective and chemoselective γ-addition of β-keto amides on isatins to afford γ-(3-hydroxy-2-oxindole)-β-keto amide structural framework under metal-free conditions. The developed method is mild, generates high yields, and is applicable for a variety of isatin electrophiles as well as β-keto amides. Moreover, the procedure is very handy and environmentally benign in nature, and provides direct access for the synthesis of diverse functionalized 3-β-keto amide-substituted 3-hydroxy-2-oxindole structural scaffolds from readily available starting materials.

A Metal-Free Approach for the Synthesis of 2-Tetralones via Carbanion-Induced Ring Transformation of 2H-Pyran-2-ones

Synthesis ◽  
2018 ◽  
Vol 50 (17) ◽  
pp. 3540-3548 ◽  
Author(s):  
Fateh Singh ◽  
Samata Shetgaonkar
Keyword(s):  
Functional Groups ◽  
Ring Transformation ◽  
Organometallic Reagents ◽  
Metal Free ◽  
Wide Range ◽  
Ultrasound Assisted ◽  
High Yields ◽  
Subsequent Acid

A metal-free, ultrasound-assisted approach for the synthesis of highly functionalized 2-tetralones in high yields is described. The process involves ring transformation of 2H-pyran-2-ones with the spirocyclic ketone 1,4-cyclohexandione monoethylene ketal to yield spiro­cyclic ketals and subsequent acid-mediated hydrolysis. This protocol is free from any organometallic reagents, is economical and tolerates a wide range of functional groups.

Facile Protocols towards C2-Arylated Benzoxazoles using Fe(III)-Catalyzed C(sp 2-H) Functionalization and Metal-Free Domino Approach

Synlett ◽  
2018 ◽  
Vol 29 (11) ◽  
pp. 1469-1478 ◽  
Author(s):  
Chandi Malakar ◽  
Nagaraju Vodnala ◽  
Raghuram Gujjarappa ◽  
Arup Kabi ◽  
Mohan Kumar ◽  
...  
Keyword(s):  
Clinical Trial ◽  
Drug Discovery ◽  
Precious Metals ◽  
Boronic Acids ◽  
The Other ◽  
Metal Free ◽  
Discovery Research ◽  
Drug Discovery Research ◽  
Wide Range ◽  
High Yields

Considering their growing attention in the field of medicinal chemistry and drug-discovery research, the facile and convenient approaches towards the preparation of 2-aryl benzoxazole derivatives have been described. The transformation is accomplished by using Fe(III)-catalyzed C–H activation of benzoxazoles with boronic acids to obtain a wide range of C2-arylated benzoxazoles in high yields. The developed method excludes the formation of self-coupling compounds as side products. On the other hand, the synthesis of the products is also achieved via a metal-free domino protocol by the reaction between 1-nitroso-2-naphthol and acetophenones using catalytic amounts of CBr4 in the presence of Cs2CO3 as base. The devised tandem method avoids the use of pre-activated α-haloketones as substrates. Due to their immense impact in marketed drugs and molecules under clinical trial, the described method can be a powerful tool for their synthesis which ­restricts the use of precious metals as catalyst.

Direct Access to Highly Functionalised Benzimidazoles and Benzoxazoles from a Common Precursor

Synthesis ◽  
2019 ◽  
Vol 51 (21) ◽  
pp. 4006-4013 ◽  
Author(s):  
Amanda Garrido ◽  
Pierre-Olivier Delaye ◽  
François Quintin ◽  
Mohamed Abarbri ◽  
Pedro Lameiras ◽  
...  
Keyword(s):  
Organic Synthesis ◽  
Building Block ◽  
Medicinal Chemistry ◽  
Direct Access ◽  
One Pot ◽  
Metal Free ◽  
Mild Conditions ◽  
Common Precursor ◽  
Biological Interest ◽  
Wide Range

Benzoxazole and benzimidazole are commonly encountered heterocycles in medicinal chemistry and their functionalisation around 1-, 2-, 5-, and/or 6-positions provides a wide range of molecules of biological interest. In this manuscript, a straightforward preparation of diversely and highly substituted benzimidazoles and benzoxazoles on these positions, from a common starting material, a 3,3-dibromoacrolein, is described. Such acrolein derivatives are almost never described in the literature or used as ‘building-block’ for organic synthesis. The double electrophilicity of this substrate was found to be advantageous for condensation with two equivalents of various 1,2-diaminobenzene or 2-aminophenol derivatives. This one-pot reaction performed under metal-free and mild conditions allows the creation of three new carbon–heteroatom bonds and affords the desired heterocycles.

Stereospecific, Palladium-catalyzed C(sp3)–H Alkenylation and Alkynylation of a Proline Derivative Enabled by 8-Aminoquinoline as a Directing Group

2020 ◽  
Author(s):  
Aleksandra Balliu ◽  
Aaltje Roelofje Femmigje Strijker ◽  
Michael Oschmann ◽  
Monireh Pourghasemi Lati ◽  
Oscar Verho
Keyword(s):  
Carboxylic Acid ◽  
Building Blocks ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
High Yields ◽  
Vinyl Iodides ◽  
Initial Results

<p>In this preprint, we present our initial results concerning a stereospecific Pd-catalyzed protocol for the C3 alkenylation and alkynylation of a proline derivative carrying the well utilized 8‑aminoquinoline directing group. Efficient C–H alkenylation was achieved with a wide range of vinyl iodides bearing different aliphatic, aromatic and heteroaromatic substituents, to furnish the corresponding C3 alkenylated products in good to high yields. In addition, we were able show that this protocol can also be used to install an alkynyl group into the pyrrolidine scaffold, when a TIPS-protected alkynyl bromide was used as the reaction partner. Furthermore, two different methods for the removal of the 8-aminoquinoline auxiliary are reported, which can enable access to both <i>cis</i>- and <i>trans</i>-configured carboxylic acid building blocks from the C–H alkenylation products.</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.

p-Sulfonic acid calix[n]arene catalyzed synthesis of bioactive heterocycles: A review

2020 ◽  
Vol 24 ◽  
Author(s):  
Bubun Banerjee ◽  
Gurpreet Kaur ◽  
Navdeep Kaur
Keyword(s):  
Supramolecular Chemistry ◽  
Sulfonic Acid ◽  
Catalytic Efficiency ◽  
The Other ◽  
Reaction Conditions ◽  
Metal Free ◽  
Bioactive Scaffolds ◽  
Wide Range ◽  
Efficient Alternative ◽  
Bioactive Heterocycles

: Metal-free organocatalysts are becoming an important tool for the sustainable developments of various bioactive heterocycles. On the other hand, during last two decades, calix[n]arenes have been gaining considerable attention due to their wide range of applicability in the field of supramolecular chemistry. Recently, sulfonic acid functionalized calix[n] arenes are being employed as an efficient alternative catalyst for the synthesis of various bioactive scaffolds. In this review we have summarized the catalytic efficiency of p-sulfonic acid calix[n]arenes for the synthesis of diverse biologically promising scaffolds under various reaction conditions. There is no such review available in the literature showing the catalytic applicability of p-sulfonic acid calix[n]arenes. Therefore, we strongly believe that this review will surely attract those researchers who are interested about this fascinating organocatalyst.

Sign in / Sign up

Export Citation Format

Share Document