Browse
Submit Data
Databases
API
Help

Dataset Information

25 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Pd^II -Catalyzed C(alkenyl)-H Activation Facilitated by a Transient Directing Group.

ABSTRACT: Palladium(II)-catalyzed C(alkenyl)-H alkenylation enabled by a transient directing group (TDG) strategy is described. The dual catalytic process takes advantage of reversible condensation between an alkenyl aldehyde substrate and an amino acid TDG to facilitate coordination of the metal catalyst and subsequent C(alkenyl)-H activation by a tailored carboxylate base. The resulting palladacycle then engages an acceptor alkene, furnishing a 1,3-diene with high regio- and E/Z-selectivity. The reaction enables the synthesis of enantioenriched atropoisomeric 2-aryl-substituted 1,3-dienes, which have seldom been examined in previous literature. Catalytically relevant alkenyl palladacycles were synthesized and characterized by X-ray crystallography, and the energy profiles of the C(alkenyl)-H activation step and the stereoinduction model were elucidated by density functional theory (DFT) calculations.

SUBMITTER: Liu M

PROVIDER: S-EPMC9320856 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

PdII -Catalyzed Enantioselective C(sp3 )-H Arylation of Cyclobutyl Ketones Using a Chiral Transient Directing Group.

Project description:The use of chiral transient directing groups (TDGs) is a promising approach for developing PdII -catalyzed enantioselective C(sp3 )-H activation reactions. However, this strategy is challenging because the stereogenic center on the TDG is often far from the C-H bond, and both TDG covalently attached to the substrate and free TDG are capable of coordinating to PdII centers, which can result in a mixture of reactive complexes. We report a PdII -catalyzed enantioselective β-C(sp3 )-H arylation reaction of aliphatic ketones using a chiral TDG. A chiral trisubstituted cyclobutane was efficiently synthesized from a mono-substituted cyclobutane through sequential C-H arylation reactions, thus demonstrating the utility of this method for accessing structurally complex products from simple starting materials. The use of an electron-deficient pyridone ligand is crucial for the observed enantioselectivity. Interestingly, employing different silver salts can reverse the enantioselectivity.

| S-EPMC7269848 | biostudies-literature

Pd-Catalyzed ?-C(sp3)-H Arylation of Free Amines Using a Transient Directing Group.

Project description:Pd(II)-catalyzed ?-C(sp3)-H arylation of primary amines is realized by using 2-hydroxynicotinaldehyde as a catalytic transient directing group. Importantly, the catalyst and the directing group loading can be lowered to 2% and 4% respectively, thus demonstrating high efficiency of this newly designed transient directing group. Heterocyclic aryl iodides are also compatible with this reaction. Furthermore, swift synthesis of 1,2,3,4-tetrahydronaphthyridine derivatives is accomplished using this reaction.

| S-EPMC5535771 | biostudies-literature

Transient directing group enabled Pd-catalyzed C-H oxygenation of benzaldehydes and benzylic amines.

Project description:We report a general protocol for ortho-C-H fluoroalkoxylation of benzaldehydes and benzylic amines utilizing an inexpensive amino amide as a transient directing group. In the presence of an electrophilic fluorinating bystanding oxidant and fluorinated alcohols, a wide range of benzaldehydes and benzylic amines could be oxygenated selectively at the ortho positions to afford fluoroalkyl aryl ethers. This elegant approach would provide appealing strategies for synthesis of drug molecules and natural products.

| S-EPMC9235058 | biostudies-literature

PdII-Catalyzed Site-selective β- and γ-C(sp3)-H Arylation of Primary Aldehydes Controlled by Transient Directing Groups.

Project description:Pd(II)-catalyzed site-selective β- and γ-C(sp3)-H arylation of primary aldehydes is developed by rational design of L,X-type transient directing groups (TDG). External 2-pyridone ligands are identified to be crucial for the observed reactivity. By minimizing the loading of acid additives, the ligand effect is enhanced to achieve high reactivities of the challenging primary aldehyde substrates. Site selectivity can be switched from the proximate to the relatively remote position by changing the bite angle of TDG to match the desired palladacycle size. Experimental and computational investigations support this rationale for designing TDG to potentially achieve remote site-selective C(sp3)-H functionalizations.

| S-EPMC9084563 | biostudies-literature

Silanol: a traceless directing group for Pd-catalyzed o-alkenylation of phenols.

Project description:A silanol-directed, Pd(II)-catalyzed C-H alkenylation of phenols is reported. This work features silanol, as a novel traceless directing group, and a directed o-C-H alkenylation of phenols. This new method allows for efficient synthesis of diverse alkenylated phenols, including an estrone derivative.

| S-EPMC3156791 | biostudies-literature

Ruthenium-Catalyzed Deuteration of Aromatic Carbonyl Compounds with a Catalytic Transient Directing Group.

Project description:A novel ruthenium-catalyzed C-H activation methodology for hydrogen isotope exchange of aromatic carbonyl compounds is presented. In the presence of catalytic amounts of specific amine additives, a transient directing group is formed in situ, which directs selective deuteration. A high degree of deuteration is achieved for α-carbonyl and aromatic ortho-positions. In addition, appropriate choice of conditions allows for exclusive labeling of the α-carbonyl position while a procedure for the preparation of merely ortho-deuterated compounds is also reported. This methodology proceeds with good functional group tolerance and can be also applied for deuteration of pharmaceutical drugs. Mechanistic studies reveal a kinetic isotope effect of 2.2, showing that the C-H activation is likely the rate-determining step of the catalytic cycle. Using deuterium oxide as a cheap and convenient source of deuterium, the methodology presents a cost-efficient alternative to state-of-the-art iridium-catalyzed procedures.

| S-EPMC8361678 | biostudies-literature

Palladium-Catalyzed C(sp3 )-H Arylation of Primary Amines Using a Catalytic Alkyl Acetal to Form a Transient Directing Group.

Project description:C-H Functionalization of amines is a prominent challenge due to the strong complexation of amines to transition metal catalysts, and therefore typically requires derivatization at nitrogen with a directing group. Transient directing groups (TDGs) permit C-H functionalization in a single operation, without needing these additional steps for directing group installation and removal. Here we report a palladium catalyzed γ-C-H arylation of amines using catalytic amounts of alkyl acetals as transient activators (e.g. commercially available (2,2-dimethoxyethoxy)benzene). This simple additive enables arylation of amines with a wide range of aryl iodides. Key structural features of the novel TDG are examined, demonstrating an important role for the masked carbonyl and ether functionalities. Detailed kinetic (RPKA) and mechanistic investigations determine the order in all reagents, and identify cyclopalladation as the turnover limiting step. Finally, the discovery of an unprecedented off-cycle free-amine directed ϵ-cyclopalladation of the arylation product is reported.

| S-EPMC6391947 | biostudies-literature

RhodiumIII-catalyzed remote difunctionalization of arenes assisted by a relay directing group.

Project description:Rhodium-catalyzed diverse tandem twofold C-H bond activation reactions of para-olefin-tethered arenes have been realized, with unsaturated reagents such as internal alkynes, dioxazolones, and isocyanates being the coupling partner as well as a relay directing group which triggers cyclization of the para-olefin group under oxidative or redox-neutral conditions. The reaction proceeded via initial ortho-C-H activation assisted by a built-in directing group in the arene, and the ortho-incorporation of the unsaturated coupling partner simultaneously generated a relay directing group that allows sequential C-H activation at the meta-position and subsequent cyclization of the para-olefins. The overall reaction represents C-C or N-C difunctionalization of the arene with the generation of diverse 2,3-dihydrobenzofuran platforms. The catalytic system proceeded with good efficiency, simple reaction conditions, and broad substrate scope. The diverse transformations of the products demonstrated the synthetic utility of this tandem reaction.

| S-EPMC9214915 | biostudies-literature

Methylene C(sp3)-H Arylation of Aliphatic Ketones Using a Transient Directing Group.

Project description:Palladium-catalyzed methylene β-C(sp3)-H arylation of aliphatic ketones using a transient directing group is developed. The use of α-benzyl β-alanine directing group that forms a six-membered chelation with palladium is crucial for promoting the methylene C(sp3)-H bond activation.

| S-EPMC5640319 | biostudies-literature

PdII -Catalyzed Enantioselective C(sp3 )-H Activation/Cross-Coupling Reactions of Free Carboxylic Acids.

Project description:PdII -catalyzed enantioselective C(sp3 )-H cross-coupling of free carboxylic acids with organoborons has been realized using either mono-protected amino acid (MPAA) ligands or mono-protected aminoethyl amine (MPAAM) ligands. A diverse range of aryl- and vinyl-boron reagents can be used as coupling partners to provide chiral carboxylic acids. This reaction provides an alternative approach to the enantioselective synthesis of cyclopropanecarboxylic acids and cyclobutanecarboxylic acids containing α-chiral tertiary and quaternary stereocenters. The utility of this reaction was further demonstrated by converting the carboxylic acid into cyclopropyl amine without loss of optical activity.

| S-EPMC6641982 | biostudies-literature