scholarly journals Direct Synthesis and Applications of Solid Silylzinc Reagents

2021 ◽  
Author(s):  
Ramesh Rasappan ◽  
Revathi Chandrasekaran ◽  
Feba Thomas Pulikkottil ◽  
Krishna Suresh
Keyword(s):  
Detrimental Effect ◽  
Functional Group ◽  
Direct Synthesis ◽  
Cross Coupling ◽  
Synthetic Methods ◽  
Synthetic Method ◽  
General Applicability ◽  
Alkyl Aryl ◽  
Synthetic Utility ◽  
First Time

The increased synthetic utility of organosilanes motivates researchers to develop a milder and more practical synthetic methods. Silylzinc reagents, which are typically the most functional group tolerant, are notoriously difficult to synthesize because they are obtained by a pyrophoric reaction of silyllithium, particularly Me3 SiLi itself prepared by the reaction of MeLi and disilane. Furthermore, the dissolved LiCl in silylzinc may have a detrimental effect. A synthetic method that can avoid silyllithium and involves a direct synthesis of silylzinc reagents from silyl halides is arguably the simplest and economical strategy. We describe for the first time, the direct synthesis of PhMe2 SiZnI and Me3 SiZnI reagents by employing a coordinating TMEDA ligand, as well as single crystal XRD structures. Importantly, they can be obtained as solid and stored for longer periods of time. We demonstrate their significance in cross-coupling of various free alkyl/aryl/alkenyl carboxylic acids with broader functional group tolerance and API derivatives. The general applicability and efficiency of solid Me3 SiZnI are shown in a wide variety of reactions including alkylation, arylation, allylation, 1,4-addition, acylation and more.

scholarly journals Direct Synthesis and Applications of Solid Silylzinc Reagents

2021 ◽  
Author(s):  
Ramesh Rasappan ◽  
Revathi Chandrasekaran ◽  
Feba Thomas Pulikkottil ◽  
Krishna Suresh
Keyword(s):  
Detrimental Effect ◽  
Functional Group ◽  
Direct Synthesis ◽  
Cross Coupling ◽  
Synthetic Methods ◽  
Synthetic Method ◽  
General Applicability ◽  
Alkyl Aryl ◽  
Synthetic Utility ◽  
First Time

The increased synthetic utility of organosilanes motivates researchers to develop a milder and more practical synthetic methods. Silylzinc reagents, which are typically the most functional group tolerant, are notoriously difficult to synthesize because they are obtained by a pyrophoric reaction of silyllithium, particularly Me3 SiLi itself prepared by the reaction of MeLi and disilane. Furthermore, the dissolved LiCl in silylzinc may have a detrimental effect. A synthetic method that can avoid silyllithium and involves a direct synthesis of silylzinc reagents from silyl halides is arguably the simplest and economical strategy. We describe for the first time, the direct synthesis of PhMe2 SiZnI and Me3 SiZnI reagents by employing a coordinating TMEDA ligand, as well as single crystal XRD structures. Importantly, they can be obtained as solid and stored for longer periods of time. We demonstrate their significance in cross-coupling of various free alkyl/aryl/alkenyl carboxylic acids with broader functional group tolerance and API derivatives. The general applicability and efficiency of solid Me3 SiZnI are shown in a wide variety of reactions including alkylation, arylation, allylation, 1,4-addition, acylation and more.

1.14 Palladium(I)-Mediated Reactions

2021 ◽  
Author(s):  
G. Maestri ◽  
A. Serafino
Keyword(s):  
Visible Light ◽  
Functional Group ◽  
Halogen Bond ◽  
Cross Coupling ◽  
Palladium Complexes ◽  
Synthetic Methods ◽  
Experimental Conditions ◽  
Alkyl Radicals ◽  
Molecular Architectures

AbstractSeveral elegant reactivities can be observed in reactions involving palladium(I) species, allowing access to molecular architectures that are often beyond the capabilities of popular diamagnetic palladium complexes. This review presents three main axes of research in this context, which have mostly emerged in the last decade. Reactions promoted by visible light enable synthetic methods that are unusual in their mild experimental conditions coupled with remarkably broad functional group tolerance. The use of discrete palladium(I) dimers as precatalysts allows one to perform a wide set of cross-coupling protocols, such as Kumada and Negishi reactions, and chalcogenation reactions, with a surgical precision on the carbon—halogen bond that is initially activated. The generation of alkyl radicals and palladium(I) species through a thermal strategy proves useful for the elaboration of substrates with several polyfluorinated fragments, which are otherwise elusive coupling partners for more common two-electron processes.

Highly Efficient Copper-Catalyzed Dehydrogenative Cross-Coupling of Azoles and α-Amino Carbonyl Compounds

Synthesis ◽  
2020 ◽  
Author(s):  
Jiu-Jian Ji ◽  
Zhi-Qiang Zhu ◽  
Zong-Bo Xie ◽  
Juan Tang ◽  
En Yuan ◽  
...  
Keyword(s):  
Carbonyl Compounds ◽  
Functional Group ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Synthetic Method ◽  
Diverse Range ◽  
Highly Efficient ◽  
Cross Coupling Reaction ◽  
Butyl Peroxide ◽  
High Yields

A novel and highly efficient dehydrogenative cross-coupling reaction between α-amino carbonyl compounds and azoles by copper catalysis using di-tert-butyl peroxide (DTBP) as an oxidant was described. A diverse range of azoles underwent the dehydrogenative imidoylation smoothly with various α-amino carbonyl compounds for the exclusive formation of the corresponding N-imidoyl azoles in high yields under air. The synthetic method has the advantages of good functional-group tolerance, wide substrate scope, excellent yields and simple operation, thus providing a convenient and practical protocol for the synthesis of various functionalized azoles.

Bimetallic BaMoO4 nanoparticles for the C–S cross-coupling of thiols with haloarenes

2020 ◽  
Vol 44 (6) ◽  
pp. 2500-2504
Author(s):  
Subhalaxmi Panda ◽  
Santosh Kumar Sahu ◽  
Pradyota Kumar Behera ◽  
Reba Panigrahi ◽  
Bamakanta Garnaik ◽  
...  
Keyword(s):  
Functional Group ◽  
Cross Coupling ◽  
Alkyl Aryl ◽  
High Yields

The C–S cross-coupling of alkyl/aryl thiols with haloarenes using BaMoO4 nanoparticles was accomplished with high yields, and good functional group tolerance and selectivity. Unactivated bromo and 4-acetyl fluoroarenes can afford thioethers in high yields.

Direct Synthesis of Vicinal Tricarbonyl Amides by Coupling of α-Oxo Acid Chlorides with Carbamoylsilanes

Synthesis ◽  
2019 ◽  
Vol 51 (15) ◽  
pp. 2977-2983
Author(s):  
Yuling Han ◽  
Yuping Li ◽  
Shenghua Han ◽  
Pengpeng Zhang ◽  
Jianxin Chen
Keyword(s):  
Oxalyl Chloride ◽  
Direct Synthesis ◽  
Coupling Reaction ◽  
Cross Coupling ◽  
Synthetic Method ◽  
Acid Chlorides ◽  
Mild Conditions ◽  
Cross Coupling Reaction ◽  
The Cross

A convenient synthetic method for vicinal tricarbonyl amides by the cross-coupling reaction of α-oxo acid chlorides with carbamoylsilanes is developed. The reaction tolerates a broad range of substituents on the amido nitrogen of carbamoylsilanes, and directly affords good yields of vicinal tricarbonyl amides under mild conditions without use of oxidants. The reaction of carbamoylsilanes with oxalyl chloride has also been explored, and is accompanied by decarbonylation to give vicinal tricarbonyl amides.

scholarly journals Nickel-Catalyzed 1,2-Diarylation of Alkenyl Carboxylates: A Gateway to 1,2,3-Trifunctionalized Building Blocks

2019 ◽  
Author(s):  
Joseph Derosa ◽  
Taeho Kang ◽  
Van Tran ◽  
Steven Wisniewski ◽  
Malkanthi Karunananda ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Functional Group ◽  
Cross Coupling ◽  
Building Blocks ◽  
Step Count ◽  
Bioactive Molecules ◽  
Aryl Iodides ◽  
Boronic Esters ◽  
Synthetic Utility

A nickel-catalyzed conjunctive cross-coupling of alkenyl carboxylic acids, aryl iodides, and aryl/alkenyl boronic esters is reported. The reaction delivers the desired 1,2-diarylated and 1,2-arylalkenylated products with excellent regiocontrol. To demonstrate the synthetic utility of the method, a representative product is prepared on gram scale and then diversified to eight 1,2,3-trifunctionalized building blocks using two-electron and one-electron logic. Using this method, three routes toward bioactive molecules are improved in terms of yield and/or step count. This method represents the first example of catalytic 1,2-diarylation of an alkene directed by a native carboxylate functional group.

scholarly journals Nickel-Catalyzed 1,2-Diarylation of Alkenyl Carboxylates: A Gateway to 1,2,3-Trifunctionalized Building Blocks

2019 ◽  
Author(s):  
Joseph Derosa ◽  
Taeho Kang ◽  
Van Tran ◽  
Steven Wisniewski ◽  
Malkanthi Karunananda ◽  
...  
Keyword(s):  
Carboxylic Acids ◽  
Functional Group ◽  
Cross Coupling ◽  
Building Blocks ◽  
Step Count ◽  
Bioactive Molecules ◽  
Aryl Iodides ◽  
Boronic Esters ◽  
Synthetic Utility

A nickel-catalyzed conjunctive cross-coupling of alkenyl carboxylic acids, aryl iodides, and aryl/alkenyl boronic esters is reported. The reaction delivers the desired 1,2-diarylated and 1,2-arylalkenylated products with excellent regiocontrol. To demonstrate the synthetic utility of the method, a representative product is prepared on gram scale and then diversified to eight 1,2,3-trifunctionalized building blocks using two-electron and one-electron logic. Using this method, three routes toward bioactive molecules are improved in terms of yield and/or step count. This method represents the first example of catalytic 1,2-diarylation of an alkene directed by a native carboxylate functional group.

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

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.

Iridium-Catalyzed Silylation of C-H bonds in Unactivated Arenes: A Sterically-Encumbered Phenanthroline Ligand Accelerates Catalysis Enabling New Reactivity

2019 ◽  
Author(s):  
Caleb Karmel ◽  
Zhewei Chen ◽  
John Hartwig
Keyword(s):  
High Activity ◽  
Functional Group ◽  
Activity Analysis ◽  
High Reactivity ◽  
High Yield ◽  
Phen Ligand ◽  
Mechanistic Studies ◽  
Phenanthroline Ligand ◽  
First Time ◽  
New System

We report a new system for the silylation of aryl C-H bonds. The combination of [Ir(cod)(OMe)]<sub>2</sub> and 2,9-Me<sub>2</sub>-phenanthroline (2,9-Me<sub>2</sub>phen) catalyzes the silylation of arenes at lower temperatures and with faster rates than those reported previously, when the hydrogen byproduct is removed, and with high functional group tolerance and regioselectivity. Inhibition of reactions by the H<sub>2</sub> byproduct is shown to limit the silylation of aryl C-H bonds in the presence of the most active catalysts, thereby masking their high activity. Analysis of initial rates uncovered the high reactivity of the catalyst containing the sterically hindered 2,9-Me<sub>2</sub>phen ligand but accompanying rapid inhibition by hydrogen. With this catalyst, under a flow of nitrogen to remove hydrogen, electron-rich arenes, including those containing sensitive functional groups, undergo silylation in high yield for the first time, and arenes that underwent silylation with prior catalysts react over much shorter times with lower catalyst loadings. The synthetic value of this methodology is demonstrated by the preparation of key intermediates in the synthesis of medicinally important compounds in concise sequences comprising silylation and functionalization. Mechanistic studies demonstrate that the cleavage of the aryl C-H bond is reversible and that the higher rates observed with the 2,9-Me<sub>2</sub>phen ligand is due to a more thermodynamically favorable oxidative addition of aryl C-H bonds.

The Total Synthesis of Rhabdastrellic Acid A

2018 ◽  
Author(s):  
Yaroslav Boyko ◽  
Christopher Huck ◽  
David Sarlah
Keyword(s):  
Total Synthesis ◽  
Late Stage ◽  
Cross Coupling ◽  
Side Chains ◽  
General Strategy ◽  
Modular Approach ◽  
Linear Sequence ◽  
Generating Sequence ◽  
First Time

<div>The first total synthesis of rhabdastrellic acid A, a highly cytotoxic isomalabaricane triterpenoid, has been accomplished in a linear sequence of 14 steps from commercial geranylacetone. The prominently strained <i>trans-syn-trans</i>-perhydrobenz[<i>e</i>]indene core characteristic of the isomalabaricanes is efficiently accessed in a selective manner for the first time through a rapid, complexity-generating sequence incorporating a reductive radical polyene cyclization, an unprecedented oxidative Rautenstrauch cycloisomerization, and umpolung 𝛼-substitution of a <i>p</i>-toluenesulfonylhydrazone with in situ reductive transposition. A late-stage cross-coupling in concert with a modular approach to polyunsaturated side chains renders this a general strategy for the synthesis of numerous family members of these synthetically challenging and hitherto inaccessible marine triterpenoids.</div>

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