A 1:1 hydrophosphination of the olefinic bond of cinnamaldehyde (and substituted ones) with Ph2PH, under argon using neat reagents, gives quantitative formation of the new tertiary phosphines Ph2PCH(Ar)CH2CHO (2) as racemic mixtures (Ar = Ph, p-tol, and p-OMe-C6H4). alpha-Methylcinnamaldehyde similarly affords Ph2PCH(Ph)CH(Me)CHO, but as a mixture of diastereomers with predominantly S,S- and R,R-chirality [diastereomeric ratio (dr) approximately 20]. In a 2:1 reaction of Ph2PH with cinnamaldehyde, hydrophosphination of both the C=C and C=O bonds takes place to give the diphosphine derivative Ph2PCH(Ph)CH2CH(OH)PPh2 (3) as a diastereomeric mixture with dr approximately 2.3. In most organic solvents, the hydrophosphination of the C=O group is reversible, leading to a dynamic equilibrium between 3 and 2, but 3 is stable in coordinating solvents such as DMSO, DMF, and pyridine. X-ray analysis of a P,P-chelated PdCl2(3) complex, formed from trans-PdCl2(PhCN)2 and 3 in MeOH, reveals that the S,S/R,R-enantiomers are favored.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1021/ic701597g | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Palladium-Catalyzed Coupling of Aryl Chlorides with Secondary Phosphines to Construct Unsymmetrical Tertiary Phosphines.
Org Lett
December 2024
School of Chemistry and Chemical Engineering, Guangxi Colleges and Universities Key Laboratory of Applied Chemistry Technology and Resource Development, Guangxi University, Nanning 530004, Guangxi, P. R. China.
The functionalization of the C-Cl bond in unactivated aryl chlorides under mild conditions presents a significant challenge. We disclose a general protocol for constructing both partially and entirely unsymmetrical tertiary phosphines through the Pd/keYPhos-catalyzed coupling of aryl chlorides with secondary phosphines under mild conditions. The reaction exhibits excellent functional group tolerance and broad substrate scopes.
View Article and Find Full Text PDFBioorthogonal cyclopropenones for investigating RNA structure.
bioRxiv
October 2024
Departments of Chemistry, University of California, Irvine, California 92697, United States.
RNA sequences encode secondary and tertiary structures that impact protein production and other cellular processes. Misfolded RNAs can also potentiate disease, but the complete picture is lacking. To establish more comprehensive and accurate RNA structure-function relationships, new methods are needed to interrogate RNA and trap native conformations in cellular environments.
View Article and Find Full Text PDFThe addition of phosphines (PR) to Michael acceptors is a key step in many Lewis-base catalysed reactions. The kinetics of the reactions of ten phosphines with ethyl acrylate, ethyl allenoate, ethyl propiolate, ethenesulfonyl fluoride, and ethyl 2-butynoate in dichloromethane at 20 °C was followed by photometric and NMR spectroscopic methods. The experimentally determined second-order rate constants show that electronic effects in sterically unencumbered phosphines affect their nucleophilicity towards different classes of Michael acceptors in the same ordering.
View Article and Find Full Text PDFRevealing the Hidden Complexity and Reactivity of Palladacyclic Precatalysts: The P(-tolyl) Ligand Enables a Cocktail of Active Species Utilizing the Pd(II)/Pd(IV) and Pd(0)/Pd(II) Pathways for Efficient Catalysis.
ACS Catal
September 2024
Department of Chemistry, University of York, York, Heslington YO10 5DD, United Kingdom.
The ligand, P(-tolyl), is ubiquitous in applied synthetic chemistry and catalysis, particularly in Pd-catalyzed processes, which typically include Pd(OAc) (most commonly used as Pd(OAc)) as a precatalyst. The Herrmann-Beller palladacycle [Pd(C^P)(μ-OAc)] (where C^P = monocyclopalladated P(-tolyl)) is easily formed from reaction of Pd(OAc) with P(-tolyl). The mechanisms by which this precatalyst system operates are inherently complex, with studies previously implicating Pd nanoparticles (PdNPs) as reservoirs for active Pd species in arylative cross-coupling reactions.
View Article and Find Full Text PDFPhosphine-Catalyzed Crossed Rauhut-Currier-Type Coupling and [3 + 2]-Cycloaddition of 2-Alkylidene-3-oxindoles with Alkenes and Allenes to Access β,γ-Unsaturated Enones and Polycyclic Oxindoles.
J Org Chem
September 2024
University of Rostock, Institute of Chemistry, Albert-Einstein-Str. 3a, Rostock 18059, Germany.
Dihydroazepino[1,2-]indole diones are tricyclic -acyl-2-alkylidene-3-oxindole enones that readily engage in tertiary phosphine-catalyzed intermolecular coupling reactions with acceptor-substituted alkenes. In these reactions, the tricyclic α-substituted enones undergo an α-alkylation with concomitant formation of a quaternary stereocenter, as well as the installation of a new double bond within the seven-membered azepane ring. The organocatalytic reaction constitutes a special case of the crossed intermolecular Rauhut-Currier reaction as the presence of the α-substituent in the enones prohibits the formation of an α,β-unsaturated product, but instead, skipped β,γ-unsaturated enones are obtained.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!