Copper-catalyzed Addition Research Articles

Copper-Catalyzed Synthesis of Difluoromethylated/C-4- and C-5-Functionalized Polycyclic Coumarin Derivatives.

A facile and novel synthetic method for the synthesis of functionalized polycyclic coumarins at the C-4 and C-5 positions is proposed for the first time, which employs copper-catalyzed addition reactions of undiscovered alkenes with difluoromethyl radicals to construct polycyclic coumarins. This strategy is characterized by high regioselectivity, easy availability of raw materials, and simple operation. Additionally, such undiscovered coumarin alkenes can be reacted with a variety of difluoromethyl precursors to obtain a wide range of valuable C-4 and C-5 position functionalized/difluoromethylated polycyclic coumarins. More importantly, some of the products showed significant inhibition of proliferation in vitro against melanoma B16-F10 and lung cancer A549 cell lines with optimal IC50 values of 8.57 and 16.04 μM, respectively.

Synthesis of Ynamides by C(sp)–H Amidation

AbstractYnamides are versatile reactive building blocks in organic chemistry; consequently, synthetic methodologies to fabricate these compounds have received extensive attention. The construction of a C–N bond between an alkyne surrogate and an amide is a powerful and practical way to access ynamides, and has been widely studied. Recently, the amidation of terminal alkynes has emerged as a straightforward alternative. This Synpacts article briefly summarizes the use of C(sp)–H amidation strategies to form ynamides; it also highlights our recent work on the synthesis of ynehydrazides through the copper-catalyzed addition of terminal alkynes to dialkyl azodicarboxylates. Finally, some future directions in this field are outlined.

Total synthesis of C37 alken-2-one temperature geomarkers

The total synthesis of the natural (8E,15E,22E)-heptatriaconta-8,15,22-trien-2-one and (15E,22E)-heptatriaconta-15,22-dien-2-one is reported. Our synthesis involved a modular and convergent approach, based on the copper-catalyzed addition of Grignard reagents to allylic olefins. The obtention of these methyl ketones is an important asset for the use of these compounds as analytical patterns with application in Earth sciences.

Copper-Catalyzed Addition of Terminal Alkynes across Dialkyl Azodicarboxylates

Key words azodicarboxylates - copper catalysis - hydrazidation - terminal alkynes - ynehydrazides

Synthesis and Antimicrobial Activity of the Pathogenic E. coli Strains of p-Quinols: Additive Effects of Copper-Catalyzed Addition of Aryl Boronic Acid to Benzoquinones.

A mild and efficient protocol for the synthesis of p-quinols under aqueous conditions was developed. The pivotal role of additives in the copper-catalyzed addition of aryl boronic and heteroaryl boronic acids to benzoquinones was observed. It was found that polyvinylpyrrolidone (PVP) was the most efficient additive used for the studied reaction. The noteworthy advantages of this procedure include its broad substrate scope, high yields up to 91%, atom economy, and usage of readily available starting materials. Another benefit of this method is the reusability of the catalytic system up to four times. Further, the obtained p-quinols were characterized on the basis of their antimicrobial activities against E. coli. Antimicrobial activity was further compared with the corresponding 4-benzoquinones and 4-hydroquinones. Among tested compounds, seven derivatives showed an antimicrobial activity profile similar to that observed for commonly used antibiotics such as ciprofloxacin, bleomycin, and cloxacillin. In addition, the obtained p-quinols constitute a suitable platform for further modifications, allowing for a convenient change in their biological activity profile.

Copper-Catalyzed Addition of Alcohols to Carbodiimides: Oxygen as an Accelerant

Copper-Catalyzed Addition of Alcohols to Carbodiimides: Oxygen as an Accelerant

Enantioselective, Copper-Catalyzed Addition of Nucleophilic Silicon to Alkenyl-Substituted Phosphine Oxides

AbstractAn enantioselective β-silylation of α,β-unsaturated phosphine oxide derivatives using a silylboronic ester as the silicon pronucleophile is reported. The reaction is catalyzed by copper salts in the presence of chiral pyridine–oxazoline (PyOx) ligands. Good to high enantioselectivities (≤95% ee) are obtained for β-aryl-substituted acceptors whereas alkyl residues in the β-position led to a lower ee value for 1° and no reaction for 2° and 3°. The new method represents another way of accessing α-chiral silanes and complements the known β-borylation.

Direct Synthesis of CF2H-Substituted 2-Amidofurans via Copper-Catalyzed Addition of Difluorinated Diazoacetone to Ynamides.

The significance of molecules containing difluoromethyl groups is driven by their potential applications in pharmaceutical and agrochemical science. Methods for the incorporation of lightly fluorinated groups such as CF2H have been less well developed. Here we report the use of difluorinated diazoacetone as a practical reagent for the direct synthesis of CF2H-substituted 2-amidofurans through addition to ynamides. These newly designed difluorinated amidofurans were elaborated to create new nitrogen-containing frameworks that would be challenging to obtain otherwise.

Mild Copper-Catalyzed Addition of Arylboronic Esters to Di-tert-butyl Dicarbonate: An Easy Access to Methyl Arylcarboxylates

AbstractAn efficient copper-catalyzed addition of arylboronic esters to (Boc)2O was developed. The reaction can be conducted under exceedingly mild conditions and is compatible with a variety of synthetically relevant functional groups. It therefore represents a useful alternative route for the synthesis of methyl arylcarboxylates. A preliminary mechanistic study indicated the involvement of an addition–elimination mechanism.

Copper-Catalyzed Addition of Grignard Reagents to in situ Generated Indole-Derived Vinylogous Imines.

Chiral indole derivatives are ubiquitous motifs in pharmaceuticals and alkaloids. Herein, the first protocol for catalytic asymmetric conjugate addition of Grignard reagents to various sulfonyl indoles, offering a straightforward approach for the synthesis of chiral 3‐sec‐alkyl‐substituted indoles in high yields and enantiomeric ratios is presented. This methodology makes use of a chiral catalyst based on copper phosphoramidite complexes and in situ formation of vinylogous imine intermediates.

Enantioselective Addition of Diethylzinc to Aromatic Aldehydes Using Chiral Oxazoline-Based Ligands

Chiral oxazoline ligands containing an aromatic ring were prepared from norephedrine and pyrrole-2-carbonitrile or 2-hydroxybenzoyl chloride. The synthesized ligands were used in the copper-catalyzed asymmetric addition of diethylzinc to aromatic aldehydes to provide optically active 1-arylpropan-1-ols with high conversion (92%) and enantioselectivity (up to 99% ee).

Regio- and Stereoselective Copper-Catalyzed Addition of γ,γ-Disubstituted Allyldiborons to Ketones

Key words copper catalysis - quaternary carbon stereocenters - allyldiborons

Copper-catalyzed regioselective alkylation of heteroarenes with functionalized alkyl halides

The Cu-catalyzed regioselective alkylation of heteroarenes with functionalized primary, secondary, and tertiary alkyl halides is reported. The reaction proceeds via the copper-catalyzed addition of alkyl radicals to a wide range of heteroarenes, including coumarin, quinolinone, naphthoquinone, and benzofuran derivatives, with a broad substrate scope and wide functional group tolerance.

Copper-Catalyzed Regioselective Synthesis of (E)-β-Fluorovinyl Sulfones.

Organofluorine compounds are finding increasing application in a variety of fields such as pharmaceutical, agrochemical, and material sciences. However, given the scarcity of fluorine-containing natural products, advancement in this area depends almost entirely on the development of new synthetic methodologies. In this article, we present the synthesis of a series of previously undescribed (E)-β-fluorovinyl sulfones via a simple copper-catalyzed addition of hydrogen fluoride to alkynyl sulfone starting materials in varying yields and E/Z selectivities. The hydrogenation of these products was also explored and compared with the hydrogenation of the related Z isomers. These new products may find interesting applications, given the versatility of vinyl sulfones in chemical synthesis and the unique properties of vinyl fluorides in biological settings.

Asymmetric Copper-Catalyzed Addition of α-Fluoronitriles to Imines

Asymmetric Copper-Catalyzed Addition of α-Fluoronitriles to Imines

Chiral NHC ligands bearing a pyridine moiety in copper-catalyzed addition of diethylzinc to nitroalkenes

Chiral N-heterocyclic carbenes, derived from amino acids containing a pyridine ring, are effective ligands in the enantioselective copper-catalyzed addition of diethylzinc to β-nitroalkenes, which provides access to chiral nitroalkanes. The advantages of this process include high yields, broad and complementary substrate scope, and good to high enantioselectivities.

Stereoselective and Regioselective Synthesis of Heterocycles via Copper-Catalyzed Additions of Amine Derivatives and Alcohols to Alkenes.

This Perspective describes the development of a family of copper(II)-catalyzed alkene difunctionalization reactions that enable stereoselective addition of amine derivatives and alcohols onto pendant unactivated alkenes to provide a range of valuable saturated nitrogen and oxygen heterocycles. 2-Vinylanilines and related substrates undergo alternative oxidative amination or allylic amination pathways, and these reactions will also be discussed. The involvement of both polar and radical steps in the reaction mechanisms have been implicated. Major product formation is a function of the lowest energy pathway, which in turn is a function of structural aspects of the various reaction components.

Electrophilic Trapping of Zirconium Enolates Obtained by Copper-Catalyzed Addition of In Situ Generated Organozirconium Reagents

Building complex structures from simple starting materials is important for effective organic synthesis. In this context, domino reactions comprising hydrozirconation of alkenes, their subsequent utilization in a copper-catalyzed conjugate addition to enones, followed by electrophilic trapping of the formed zirconium enolates with activated alkene and carbocations are described. Reactivity of metal enolates was studied by DFT calculations.

Copper-catalyzed direct alkylation of heteroarenes

An efficient and broadly applicable process is reported for the direct alkylation of C-H bonds in heteroarenes, privileged scaffolds in many areas of science. This reaction is based on the copper-catalyzed addition of alkyl radicals generated from activated secondary and tertiary alkyl bromides to a wide range of arenes, including furans, thiophenes, pyrroles, and their benzo-fused derivatives, as well as coumarins and quinolinones.

Copper-Catalyzed Addition of H-P(O) Bonds to Arynes.

An efficient P-arylation of secondary phosphine oxides has been achieved through the ligand-free copper-catalyzed addition of H-P(O) bonds to in situ generated arynes at room temperature. This transformation provides a straightforward route to the formation of the aryl-P bond with wide functional group compatibility, which produces arylphosphine oxides in up to 99% yield.