Browse
Submit Data
Databases
API
Help

Dataset Information

26 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Oxidative Heck vinylation for the synthesis of complex dienes and polyenes.

ABSTRACT: We introduce an oxidative Heck reaction for selective complex diene and polyene formation. The reaction proceeds via oxidative Pd(II)/sulfoxide catalysis that retards palladium-hydride isomerizations which previously limited the Heck manifold's capacity for furnishing stereodefined conjugated dienes. Limiting quantities of nonactivated terminal olefins (1 equiv) and slight excesses of vinyl boronic esters (1.5 equiv) that feature diverse functionality can be used to furnish complex dienes and polyenes in good yields and excellent selectivities (generally E:Z = >20:1; internal:terminal = >20:1). Because this reaction only requires prior activation of a single vinylic carbon, improvements in efficiency are observed for synthetic sequences relative to ones featuring reactions that require activation of both coupling partners.

SUBMITTER: Delcamp JH

PROVIDER: S-EPMC4084759 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Oxidative Heck vinylation for the synthesis of complex dienes and polyenes.

Delcamp Jared H JH Gormisky Paul E PE White M Christina MC

Journal of the American Chemical Society 20130530 23

We introduce an oxidative Heck reaction for selective complex diene and polyene formation. The reaction proceeds via oxidative Pd(II)/sulfoxide catalysis that retards palladium-hydride isomerizations which previously limited the Heck manifold's capacity for furnishing stereodefined conjugated dienes. Limiting quantities of nonactivated terminal olefins (1 equiv) and slight excesses of vinyl boronic esters (1.5 equiv) that feature diverse functionality can be used to furnish complex dienes and po ...[more]

PMID: 23701421

Similar Datasets

Catalyst-controlled regioselectivity in the synthesis of branched conjugated dienes via aerobic oxidative Heck reactions.

Project description:Pd-catalyzed aerobic oxidative coupling of vinylboronic acids and electronically unbiased alkyl olefins provides regioselective access to 1,3-disubstituted conjugated dienes. Catalyst-controlled regioselectivity is achieved by using 2,9-dimethylphenanthroline as a ligand. The observed regioselectivity is opposite to that observed from a traditional (nonoxidative) Heck reaction between a vinyl bromide and an alkene. DFT computational studies reveal that steric effects of the 2,9-dimethylphenanthroline ligand promote C-C bond formation at the internal position of the alkene.

| S-EPMC3495987 | biostudies-literature

Highly Regio- and Stereoselective Catalytic Synthesis of Conjugated Dienes and Polyenes.

Project description:Conjugated dienes and polyenes are typically synthesized by sequential introduction of C?C bonds. Here, we report a practical and scalable, catalytic dienylation that is highly regio- and stereoselective for both C?C bonds. The reaction is enabled by a stereoselective palladium-catalyzed cross-coupling that is preceded by a regioselective base-induced ring opening of readily available sulfolenes. The dienylation reaction is particularly useful for the synthesis of synthetically challenging dienes containing cis double bonds. We also show that the reaction can serve as a synthetic platform for the construction of conjugated polyenes.

| S-EPMC6171353 | biostudies-literature

Nickel-catalyzed divergent Mizoroki-Heck reaction of 1,3-dienes.

Project description:Developing efficient strategies to realize divergent arylation of dienes has been a long-standing synthetic challenge. Herein, a nickel catalyzed divergent Mizoroki-Heck reaction of 1,3-dienes has been demonstrated through the regulation of ligands and additives. In the presence of Mn/NEt3, the Mizoroki-Heck reaction of dienes delivers linear products under Ni(dppe)Cl2 catalysis in high regio- and stereoselectivities. With the help of catalytic amount of organoboron and NaF, the use of bulky ligand IPr diverts the selectivity from linear products to branched products. Highly aryl-substituted compounds can be transformed from dispersive Mizoroki-Heck products programmatically. Preliminary experimental studies are carried out to elucidate the role of additives.

| S-EPMC9902549 | biostudies-literature

Pd-catalyzed decarboxylative Heck vinylation of 2-nitrobenzoates in the presence of CuF?.

Project description:A new protocol for the decarboxylative Heck vinylation of benzoic acids is disclosed. In the presence of a catalyst system generated in situ from Pd(OAc)? (2 mol %), CuF? (2 equiv), and benzoquinone (0.5 equiv) in NMP, a wide range of olefins were coupled with various 2-nitrobenzoates at 130 ° C with the release of carbon dioxide to afford the corresponding vinyl arenes in good yields.

| S-EPMC2887305 | biostudies-literature

Convergent and stereospecific synthesis of complex skipped polyenes and polyunsaturated fatty acids.

Project description:Skipped polyenes (that is, 1,4-dienes and higher homologues) are stereodefined components of a vast array of biologically important natural products, including polyunsaturated fatty acids. Although widespread in nature, these architectures are generally considered to represent significant barriers to efficient chemical synthesis. Partial reduction of skipped poly-ynes provides a pathway to a subset of such structures, but general chemical methods for the preparation of skipped polyenes that contain varied stereochemistries and substitution patterns are lacking. Here, we describe a metal-promoted reductive cross-coupling reaction between vinylcyclopropanes and alkynes (or vinylsilanes) that provides stereoselective access to a diverse array of skipped polyenes through a process that establishes one C-C bond, generates up to three stereodefined alkenes, and can be used to introduce stereogenic centres at the central positions of the skipped polyene motif. We also demonstrate the significance of the present bond construction by preparing substituted and stereodefined polyunsaturated synthetic fatty acids.

| S-EPMC2909609 | biostudies-literature

Low Pressure Vinylation of Aryl and Vinyl Halides via Heck-Mizoroki Reactions Using Ethylene.

Project description:Aryl bromides and iodides in the presence of catalytic amounts of a palladacycle derived from acetophenone oxime and 2 equivalents of potassium acetate react with ethylene under ambient pressure (15-30 psi) to give the corresponding vinylarenes. The reactions work with both electron-deficient and electron-rich aryl compounds and tolerate wide variety of common functional groups. Vinyl bromides lead to 1,3-dienes in moderate yields.

| S-EPMC2910319 | biostudies-literature

Development of a C-C Bond Cleavage/Vinylation/Mizoroki-Heck Cascade Reaction: Application to the Total Synthesis of 14- and 15-Hydroxypatchoulol.

Project description:A C-C bond cleavage/vinylation/Mizoroki-Heck cascade reaction has been developed to provide access to densely functionalized bicyclo[2.2.2]octane frameworks. The sequence proceeds through the coupling of dihydroxylated pinene derivatives, prepared from carvone, with gem-dichloroalkenes. The method was applied to 12-step total syntheses of both 14- and 15-hydroxypatchoulol, which provided unambiguous support for the structure of the natural products and corrects a misassignment in the isolation report.

| S-EPMC9635941 | biostudies-literature

Synthesis of Cross-Conjugated Polyenes via Palladium-Catalyzed Oxidative C-C Bond Forming Cascade Reactions of Allenes.

Project description:An efficient palladium-catalyzed oxidative C-C bond forming cascade reaction of allenes involving a coupling between an enallene and an allenyne followed by a carbocyclization of the generated Pd-intermediate was developed. This cascade reaction afforded functionalized cross-conjugated polyenes. The enallene is initially activated by palladium and reacts with the allenyne to give the cross-conjugated polyenes.

| S-EPMC7311062 | biostudies-literature

Pd-Catalyzed Heck-Type Reactions of Allenes for Stereoselective Syntheses of Substituted 1,3-Dienes.

Project description:A highly stereoselective Pd-catalyzed Heck-type reaction of allenes in which the stereochemistry of both olefins is set simultaneously was developed. The ligand CyJohnPhos was crucial to achieving stereoselectivity, while minimizing isomerization of the starting material through hydropalladation. The stereodetermining factors were proposed to be A1,3 strain between the catalyst and allene substituent, which influences the σ-π-σ equilibrium of the coupled allene intermediate, as well as eclipsing interactions of R groups in the β-hydride elimination. Good functional group tolerance and stereoselectivities for formation of the Z,E isomer were demonstrated. The methodology was further expanded to include the regioselective formation of 2,4-dienoates and 2,4-dienamides with a variety of substitution patterns, albeit in reduced stereoselectivities favoring the E,E isomer. A plausible mechanism is proposed to account for the observed selectivities and substituent effects.

| S-EPMC8727505 | biostudies-literature

Asymmetric oxidative cation/olefin cyclization of polyenes: evidence for reversible cascade cyclization.

Project description: Not available

| S-EPMC2908993 | biostudies-literature