Palladium-catalyzed Cascade Reaction Research Articles

Vinylogous Elimination/C-H Functionalization/Allylation Cascade Reaction of Allenoate Adducts: Synthesis of Ring-Fused Dihydropyridinones.

A palladium-catalyzed cascade reaction of β'-allenoate adducts with aryl/heteroaryl carboxamides through a vinylogous elimination/C-H functionalization/intramolecular allylation reaction sequence has been developed with high Z stereoselectivity. Various ring-fused dihydropyridinones bearing an α,β-unsaturated ester substituent are obtained. It is the first example of application of the allenoate adducts to C-H functionalization annulations as practical precursors of hard-to-get functionalized electron-deficient 1,3-butadienes. Using air as the terminal oxidant also shows a great advantage in environmental friendliness.

Palladium-catalyzed cascade synthesis of spirocyclic oxindoles via regioselective C2-H arylation and C8-H alkylation of naphthalene ring

A simultaneous C2-H arylation and C8-H alkylation of naphthalene ring has been achieved by palladium-catalyzed cascade reaction of N-(2-halophenyl)-2-(naphthalen-1-yl)acrylamides with aryl iodides, which provides an efficient method for synthesizing various aryl-substituted spirocyclic oxindoles. The protocol enables three CC bonds formation via an intramolecular Heck reaction and sequentially regioselective CH bond activation.

Palladium-catalyzed regioselective cascade reaction of carbon dioxide, amines and allenes for the synthesis of functionalized carbamates

A palladium-catalyzed regioselective three-component cascade reaction of carbon dioxide, amines and allenes has been developed, providing an expedient and practical method for the construction of a range of functionalized carbamates containing dihydrobenzofuran or indole moiety in moderate to excellent yields. The broad substrate scope, good functional group tolerance and excellent chemo- and regioselectivity are the features of the transformation.

Palladium-Catalyzed Cascade Reactions of δ-Ketonitriles with Arylboronic Acids: Synthesis of Pyridines.

This study presents the first example of the Pd-catalyzed cascade reactions of 5-oxohexanenitrile with arylboronic acids, affording important synthon 2-methylpyridines that can be further translated through C(sp3)-H functionalization to construct pyridine derivatives. Furthermore, this chemistry allows 5-oxo-5-arylpentanenitrile to react with arylboronic acids to provide unsymmetrical 2,6-diarylpyridines. This protocol paves the way for the practical and atom economical syntheses of valuable pyridines with broad functional groups in moderate to excellent yields under mild conditions.

Palladium-Catalyzed Borylation Cyclization Cascade Reactions Generating 5- and 6-Membered Heterocycles

Key words palladium catalysis - borylation - heterocycles - cyclopropanation

Palladium-catalyzed cascade reactions of enynones and isocyanides: access towards functionalized ketenimine and its application.

Palladium-catalyzed cascade reactions of enynones and isocyanides have been disclosed. This strategy allows for the synthesis of structurally unusual furan-incorporated ketenimines, which are stable and can undergo a formal [4+1] annulation with another isocyanide to yield indenone derivatives.

Facile access to 2,2-diaryl 2H-chromenes through a palladium-catalyzed cascade reaction of ortho-vinyl bromobenzenes with N-tosylhydrazones.

A palladium-catalyzed cascade reaction of ortho-vinyl bromobenzenes with N-tosylhydrazones has been developed, which provides a facile approach to 2,2-disubstituted 2H-chromenes. The migration of palladium from the aryl to vinyl position is crucial, as the in situ produced vinyl palladium intermediate could further react with diazo compounds to generate the reactive species for the sequential annulation.

One-pot synthesis of benzofluorene fused aromatic hydrocarbons

A new and efficient synthetic approach for the one-pot construction of benzofluorene fused aromatic hydrocarbons was developed via a transient-directing group strategy. The palladium-catalyzed cascade reaction proceeded via consecutive arylation, cyclization and aromatization steps. Moderate to good yields along with broad functional group tolerance were achieved under mild reaction conditions.

Chemists synthesize natural insecticide in 16 steps

Although chemists have known about the molecule perseanol since the 1990s, no one has completed a total synthesis of the complex, polycyclic insecticide, until now. California Institute of Technology chemistry professor Sarah E. Reisman and graduate students Arthur Han and Yujia Tao constructed perseanol in just 16 steps, starting from a commercially available vinylogous ester and pulegone—a compound found in plants like catnip. The chemists’ strategy features a one-pot palladium-catalyzed cascade and carbon monoxide insertion reaction that stitches together most of perseanol’s polycyclic core (Nature 2019, DOI: 10.1038/s41586-019-1580-x). Learn more at cenm.ag/perseanol. Subscribe to our YouTube channel to catch all of our chemistry news videos. The following is the script for the video. We have edited the interviews within for length and clarity. Matt Davenport: In the 1990s, a team of scientists was in Tenerife, in the Canary Islands, hoping to find some interesting molecules in the island’s plants. They

Palladium-Catalyzed Cascade Reaction of o-Cyanobiaryls with Arylboronic Acids: Synthesis of 5-Arylidene-7-aryl-5H-dibenzo[c,e]azepines.

A palladium-catalyzed cascade reaction of 2'-acetyl-[1,1'-biphenyl]-2-carbonitriles with arylboronic acids is developed. This reaction affords a new class of seven-membered 5-arylidene-7-aryl-5H-dibenzo[c,e]azepines with good functional group compatibility and selectivity. Reaction mechanistic study suggests that this transformation involves carbopalladation of nitrile and subsequent intramolecular cyclization followed by oxidative Heck coupling.

Palladium-Catalyzed Stereospecific Oxidative Cascade Reaction of Allenes for the Construction of Pyrrole Rings: Control of Reactivity and Selectivity

A palladium-catalyzed oxidative cascade reaction of α-tosylamide allenes has been developed. The reactivity of the allenes is controlled by the tosylamide group. In the presence of terminal alkynes...

Synthesis of bicyclic ethers by a palladium-catalyzed oxidative cyclization-redox relay-π-allyl-Pd cyclization cascade reaction.

Bicyclic ether scaffolds are found in a variety of natural products and are of interest in probe and drug discovery. A palladium-catalyzed cascade reaction has been developed to provide efficient access to these scaffolds from readily available linear diene-diol substrates. A Pd redox-relay process is used strategically to transmit reactivity between an initial oxypalladative cyclization and a subsequent π-allyl-Pd cyclization at remote sites. The reaction affords a variety of bicyclic ether scaffolds with complete diastereoselectivity for cis-ring fusion.

A visible-light-induced cascade reaction of etherification/C-C cyclization: efficient synthesis of dibenzo[b,d]oxepin-7(6H)-ones.

A visible-light-induced palladium-catalyzed cascade reaction was developed by etherification/C-C coupling cyclization of α-bromoacetophenones with phenols. A series of dibenzo[b,d]oxepin-7(6H)-one derivatives were efficiently synthesized by using this method in good yields. Furthermore, this method was applied to the synthesis of protosappanin A. The protocol has advantages such as simple reaction conditions, wide range of substrates and high reaction efficiency.

A palladium-catalyzed multi-component annulation approach towards the synthesis of phenanthrenes.

An efficient palladium-catalyzed three-component cascade reaction has been developed for the facile construction of phenanthrene frameworks. The transformation is driven by a controlled reaction sequence of Suzuki-Miyaura coupling followed by the insertion of alkynes, and finally, annulation to yield phenanthrene derivatives via C-H activation. This methodology is able to accommodate a variety of substrates and affords the anticipated products in good to excellent yields.

Palladium-catalyzed cascade reactions of alkene-tethered carbamoyl chlorides with N-tosyl hydrazones: synthesis of alkene-functionalized oxindoles.

A palladium-catalyzed cascade reaction of alkene-tethered carbamoyl chlorides with N-tosyl hydrazones is described. It provided a new way to synthesize various alkene-functionalized oxindoles bearing an all-carbon quaternary center. The olefin moieties could serve as versatile handles for further elaboration. This transformation was highly efficient and showed good functional group tolerance.

Construction of Quaternary Stereocenters by Palladium-Catalyzed Carbopalladation-Initiated Cascade Reactions.

The enantioselective synthesis of molecules containing quaternary stereocenters is a field of intense research interest and development. Among the known organic transformations, carbopalladation-initiated domino transformations constitutes a general method for the construction of compounds containing cyclic or spiro quaternary stereocenters. In this Minireview, recent achievements in palladium-catalyzed domino Heck/C-H functionalizations and developments in enantioselective carbopalladation-initiated domino processes are summarized.

Palladium/Norbornene Chemistry: Synthesis of Norbornene-Containing Arylsilanes Involving Double C-Si Bond Formation.

A novel palladium-catalyzed three-component cascade reaction of aryl halides with norbornene and hexamethyldisilane has been described, which allows the simultaneous construction of two C-Si bonds and one C-C bond. The method achieves ortho C-H functionalization of aryl halides through the formation of the five-membered palladacycle, leading to norbornene-containing arylsilanes.

Molecular Diversity of Cyclooctatetraenes through Palladium‐Catalyzed Cascade Reactions

AbstractNo Abstractmagnified image

Recent Progress in Palladium-Catalyzed Cascade Cyclizations for Natural Product Synthesis

Cascade reactions (also represented as domino reactions) realize the step-economical direct construction of natural product core structures. The use of atom-economical elementary reactions in cascade processes can minimize waste production and avoid prefunctionalization of the substrates. Palladium catalysis, which promotes a variety of atom-economical elementary reactions, has long been used as a powerful approach to the direct formation of complex heterocycles. In this short review, palladium-catalyzed cascade reactions for the construction of core structures of natural products reported in the last decade­ are highlighted.1 Introduction2 Reactions Terminated with Heteronucleophiles2.1 Termination with Nitrogen Nucleophiles2.2 Termination with Oxygen Nucleophiles3 Reactions Terminated with Carbon Functional Groups3.1 Termination with Carbon Nucleophiles3.2 Termination with Heck-Type Reactions4 Conclusion

Palladium-Catalyzed Four-Component Cascade Reaction for the Synthesis of Highly Functionalized Acyclic O,O-Acetals.

A palladium-catalyzed four-component cascade reaction of carbon dioxide, amines, allenyl ethers, and aryl iodides has been developed for the first time. The novel reaction allows simultaneous construction of three different new bonds (C-N, C-O, and C-C) in a single step, affording an efficient method for the synthesis of a variety of highly functionalized acyclic O,O-acetals. Excellent chemo- and regioselectivity, wide substrate scope, and good functional group tolerance are features of the method.