Palladium-catalyzed reaction of vinyl triflates and vinyl/aryl halides with 4-alkynoic acids: regio- and stereoselective synthesis of (E)-.delta.-vinyl/aryl-.gamma.-methylene-.gamma.-butyrolactones
摘要:
The palladium-catalyzed reaction of vinyl triflates and vinyl/aryl halides with 4-pentynoic acid, 2,2-disubstituted 4-pentynoic acids, and 5-substituted 4-pentynoic acids produced regio- and stereoselectively the corresponding (E)-delta-vinyl/aryl-gamma-methylene-gamma-butyrolactones in good to high yield. Reactions were carried out in the presence of catalytic amounts of Pd(OAc)2(PPh3)2 or Pd(PPh3)4, Et3N, and n-Bu4NCl. The presence of chloride anions was found to be necessary to obtain the best results. The proposed mechanism involves an intramolecular nucleophilic attack of the carboxylate anion on the palladium-coordinated carbon-carbon triple bond and subsequent reductive elimination of Pd(0) species from the resulting sigma-vinylpalladium complex which regenerates the catalyst and releases the exocyclic enol lactone.
A visible-light-driven carboxylation of aryl and alkenyl triflates with CO2 is developed by using a combination of Pd and photoredox catalysts. This reaction proceeds under mild conditions and can be applied to a wide range of substrates including acyclic alkenyl triflates.
Pd-Catalyzed Difluoromethylation of Vinyl Bromides, Triflates, Tosylates, and Nonaflates
作者:Dalu Chang、Yang Gu、Qilong Shen
DOI:10.1002/chem.201500551
日期:2015.4.13
Pd‐catalyzed difluoromethylation of di‐, tri‐ or tetra‐substituted vinyl bromides, triflates, tosylates and nonaflates under mild conditions is described. The reaction tolerates a wide range of functional groups, such as bromide, chloride, fluoride, ester, amine, nitrile, and protected carbonyl, thus providing a general route for the preparation of difluoromethylated alkenes.
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<b>-Alkynyltrifluoroacetanilides Through the Aminopalladation-Reductive Elimination Process</b>
作者:Sandro Cacchi、Giancarlo Fabrizi、Luca Parisi
DOI:10.1055/s-2004-815993
日期:——
The functionalized pyrrole nucleus contained in the indole system has been assembled via the palladium-catalyzed reaction of o-alkynyltrifluoroacetanilides with organic halides/triflates or allyl carbonates. In the presence of carbon monoxide, a three-component reaction can take place and indole derivatives incorporating a molecule of carbon monoxide have been obtained.
Multimetallic Ni- and Pd-Catalyzed Cross-Electrophile Coupling To Form Highly Substituted 1,3-Dienes
作者:Astrid M. Olivares、Daniel J. Weix
DOI:10.1021/jacs.7b13601
日期:2018.2.21
synthesis of highly substituted 1,3-dienes from the coupling of vinyl bromides with vinyl triflates is reported for the first time. The coupling is catalyzed by a combination of (5,5'-bis(trifluoromethyl)-2,2'-bipyridine)NiBr2 and (1,3-bis(diphenylphosphino)propane)PdCl2 in the presence of a zinc reductant. This method affords tetra- and penta-substituted 1,3-dienes that would otherwise be difficult
Electrochemical Deoxygenative Thiolation of Preactivated Alcohols and Ketones
作者:Feng Zhang、Yang Wang、Yi Wang、Yi Pan
DOI:10.1021/acs.orglett.1c02738
日期:2021.10.1
This work describes an electrochemically promoted nickel-catalyzed deoxygenative thiolation of alcohols and ketones under mild conditions. Excellent substrate tolerance and good chemical yields can be achieved by graphene/nickel foam electrodes in an undivided cell. Further study to gain mechanistic insight into this electrochemical cross-coupling has been carried out.