26114-87-4Relevant academic research and scientific papers
Kinetic Resolution of 5-Substituted Cyclohexenols by Palladium-Catalyzed Asymmetric Redox-Relay Heck Reaction
Li, Hao,Gao, Ang,Liu, Xiu-Yan,Ding, Chang-Hua,Xu, Bin,Hou, Xue-Long
supporting information, p. 159 - 166 (2016/12/24)
The kinetic resolution of 2-substituted-cyclohexenols via palladium-catalyzed asymmetric redox-relay Heck reaction was realized, providing optically active 2-substituted cyclohexenols and trans-3,5-disubstituted cyclohexan-1-ones in high yield and good en
Mechanistic Studies on a Cu-Catalyzed Asymmetric Allylic Alkylation with Cyclic Racemic Starting Materials
Rideau, Emeline,You, Hengzhi,Sidera, Mireia,Claridge, Timothy D. W.,Fletcher, Stephen P.
supporting information, p. 5614 - 5624 (2017/04/27)
Mechanistic studies on Cu-catalyzed asymmetric additions of alkylzirconocene nucleophiles to racemic allylic halide electrophiles were conducted using a combination of isotopic labeling, NMR spectroscopy, kinetic modeling, structure-activity relationships, and new reaction development. Kinetic and dynamic NMR spectroscopic studies provided insight into the oligomeric Cu-ligand complexes, which evolve during the course of the reaction to become faster and more highly enantioselective. The Cu-counterions play a role in both selecting different pathways and in racemizing the starting material via formation of an allyl iodide intermediate. We quantify the rate of Cu-catalyzed allyl iodide isomerization and identify a series of conditions under which the formation and racemization of the allyl iodide occurs. We developed reaction conditions where racemic allylic phosphates are suitable substrates using new phosphoramidite ligand D. D also allows highly enantioselective addition to racemic seven-membered-ring allyl chlorides for the first time.1H and2H NMR spectroscopy experiments on reactions using allylic phosphates showed the importance of allyl chloride intermediates, which form either by the action of TMSCl or from an adventitious chloride source. Overall these studies support a mechanism where complex oligomeric catalysts both racemize the starting material and select one enantiomer for a highly enantioselective reaction. It is anticipated that this work will enable extension of copper-catalyzed asymmetric reactions and provide understanding on how to develop dynamic kinetic asymmetric transformations more broadly.
Asymmetric palladium-catalyzed allylic alkylation using dialkylzinc reagents: A remarkable ligand effect
Misale, Antonio,Niyomchon, Supaporn,Luparia, Marco,Maulide, Nuno
supporting information, p. 7068 - 7073 (2014/07/08)
A serendipitously discovered palladium-catalyzed asymmetric allylic alkylation reaction with diorganozinc reagents, which displays broad functional group compatibility, is reported. This novel transformation hinges on a remarkable ligand effect which overrides the standard "umpolung" reactivity of allyl-palladium intermediates in the presence of dialkylzincs. Owing to its mild conditions, enantioselective allylic alkylations of racemic allylic electrophiles are possible in the presence of sensitive functional groups. Umpole-me-not: A serendipitously discovered palladium-catalyzed asymmetric allylic alkylation reaction with diorganozinc reagents displays broad functional group compatibility. This novel transformation hinges on a remarkable ligand effect which overrides the standard "umpolung" reactivity of allyl-palladium intermediates in the presence of dialkylzinc compounds.
Palladium-catalyzed decarboxylative asymmetric allylic alkylation of enol carbonates
Trost, Barry M.,Xu, Jiayi,Schmidt, Thomas
supporting information; experimental part, p. 18343 - 18357 (2010/04/25)
Palladium-catalyzed decarboxylative asymmetric allylic alkylation (DAAA) of allyl enol carbonates as a highly chemo-, regio-, and enantioselective process for the synthesis of ketones bearing either a quaternary or a tertiary R-stereogenic center has been investigated in detail. Chiral ligand L4 was found to be optimal in the DAAA of a broad scope of cyclic and acyclic ketones including simple aliphatic ketones with more than one enolizable proton. The allyl moiety of the carbonates has been extended to a variety of cyclic or acyclic disubstituted allyl groups. Our mechanistic studies reveal that, similar to the direct allylation of lithium enolates, the DAAA reaction proceeds through an "outer sphere" S N2 type of attack on the π-allylpalladium complex by the enolate. An important difference between the DAAA reaction and the direct allylation of lithium enolates is that in the DAAA reaction, the nucleophile and the electrophile were generated simultaneously. Since the π-allylpalladium cation must serve as the counterion for the enolate, the enolate probably exists as a tight-ion-pair. This largely prevents the common side reactions of enolates associated with the equilibrium between different enolates. The much milder reaction conditions as well as the much broader substrate scope also represent the advantages of the DAAA reaction over the direct allylation of preformed metal enolates.
Investigation of the aqueous transmetalation of π-allylpalladium with indium salt: The use of the Pd(OAc)2-TPPTS catalyst
Fontana, Gianfranco,Lubineau, Andre,Scherrmann, Marie-Christine
, p. 1375 - 1380 (2007/10/03)
π-Allylpalladium complexes could be generated in water by the palladium(0) water soluble catalyst prepared in situ from palladium acetate and TPPTS. These complexes were transmetalated with indium to react with benzaldehyde. The aqueous solution of Pd(0)(TPPTS)n could be reused without deterioration of the catalyst in the first and second recycling. The system proved to be efficient with primary and secondary allylic substrates. The stereochemical outcome of the allylation through umpolung of allylpalladium, was also studied using models with a restraint conformation. The Royal Society of Chemistry 2005.
Photochemical rearrangement of 2-phenylthio-3-aminocyclohexanols. New access to deoxyazasugars and their derivatives
Gravel, Denis,Amoozadeh, Ali,Wang, Yuan
, p. 8039 - 8042 (2007/10/03)
This paper reports the regioselective photorearrangement of 2- phenylthio-3-aminocyclohexanols to deoxyazasugars and their derivatives. These give access to variously substituted piperidines, amino-sulfones, - sulfoxides and -acids.
Palladium-Catalyzed Cross-Coupling of Aryl Halides and Olefinic Epoxides via Palladium Migration
Larock, Richard C.,Leung, Wai-Yee
, p. 6244 - 6245 (2007/10/02)
The palladium-catalyzed cross-coupling of aryl halides and olefinic epoxides bearing one to ten carbons between the two functional groups afford good yields of arylated allylic alcohols by a palladium migration process.
