Allyl Cross-Coupling Reactions Research Articles

Nickel-catalyzed allyl–allyl coupling reactions between 1,3-dienes and allylboronates

A regiospecific allyl-allyl coupling reaction between 1,3-dienes and allylboronates has been demonstrated under nickel catalysis. Salient features of this method include the earth-abundant metal catalyst, excellent regioselectivity and good functional group tolerance. Notably, even congested allyl substrates can also be applied to this protocol, thus allowing for the rapid preparation of a series of valuable 1,5-dienes.

Allyl–Allyl Cross-Coupling Reactions Catalyzed by Triflimide

Allyl–Allyl Cross-Coupling Reactions Catalyzed by Triflimide

Palladium-Catalyzed Allylic Cross-Coupling Reactions of Primary and Secondary Homoallylic Electrophiles

The Pd(0)-catalyzed allylic cross-coupling of homoallylic tosylate substrates using boronic acids and pinacol esters is reported. The reaction uses 2-(4,5-dihydro-2-oxazolyl)quinoline (quinox) as a ligand and is performed at ambient temperature. The scope of the reaction is broad in terms of both the boronate transmetalating reagent and the substrate and includes secondary tosylates. Mechanistic studies support an alkene-mediated S(N)2-type stereoinvertive oxidative addition of unactivated primary and secondary alkyl tosylates.

Palladium‐Catalyzed Allyl Cross‐Coupling Reactions with In Situ Generated Organoindium Reagents

Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions, using allylindium generated in situ from allyl halides and indium, is demonstrated. Allylindium compounds may be effective nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions. A variety of allyl halides, such as allyl iodide, allyl bromide, crotyl bromide, prenyl bromide, geranyl bromide, and 3-bromocyclohexene afforded the allylic cross-coupling products in good to excellent yields. Stereochemistry of the double bond is retained in the allylic cross-coupling reactions. Electrophilic cross-coupling partners, such as aryl and vinyl halides, dibromoolefin, alkynyl iodide, and aryl and vinyl triflates participate in these reactions. The presence of various substituents, such as n-butyl, ketal, acetyl, ethoxycarbonyl, nitrile, N-phenylamido, nitro, and chloride groups on the aromatic ring of electrophilic coupling partners showed little effect on the efficiency of the reactions. The present conditions work equally well for not only intermolecular but also intramolecular palladium-catalyzed cross-coupling reactions. These methods provide an efficient synthetic method for the introduction of an allyl group, which can be easily further functionalized to afford an sp(2)- and sp-hybridized carbon. The present method complements existing synthetic methods as a result of advantageous features such as easy preparation and handling, thermal stability, high reactivity and selectivity, operational simplicity, and low toxicity of allylindium reagents.

Xantphos as an Efficient Ligand for Palladium-Catalyzed Cross-Coupling Reactions of Aryl Bromides and Triflates with Allyl Acetates and Indium

Xantphos was found to be an efficient ligand for palladium-catalyzed allyl cross-coupling reactions of aryl bromides and triflates with allylindium reagents generated in situ from allyl acetates and indium. These reactions occur in high yield with good functional group tolerance.

Cooperative Catalysis by Indium and Palladium for the Allyl Cross-Coupling Reactions

Cooperative Catalysis by Indium and Palladium for the Allyl Cross-Coupling Reactions

Inter‐ and Intramolecular Palladium‐Catalyzed Allyl Cross‐Coupling Reactions Using Allylindium Generated In Situ from Allyl Acetates, Indium, and Indium Trichloride

Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions using allylindium generated in situ by treatment of allyl acetates with indium and indium trichloride in the presence of Pd(0) catalyst and nBuNMe(2) in DMF were successfully demonstrated. Allylindium species generated in situ by reductive transmetalation of pi-allylpalladium(II) complexes, obtained from a variety of allyl acetates in the presence of Pd(0) catalyst together with indium and indium trichloride, were found to be capable of acting as effective nucleophilic coupling partners in Pd-catalyzed cross-coupling reactions. A variety of allyl acetates such as but-1-en-3-yl acetate, crotyl acetate, and 2-methylallyl acetate afforded the corresponding allylic compounds in good yields in cross-coupling reactions. Various electrophilic cross-coupling partners such as aryl iodides and vinyl bromides and triflates participate in these reactions. Not only intermolecular but also intramolecular Pd-catalyzed cross-coupling reactions work equally well to produce the desired allylic coupling products in good yields.

Synthesis of Chromane Derivatives by Palladium‐Catalyzed Intramolecular Allylation of Aldehydes with Allylic Acetates or Chlorides Using Indium and Indium(III) Chloride.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of Chromane Derivatives by Palladium-Catalyzed Intramolecular Allylation of Aldehydes with Allylic Acetates or Chlorides Using Indium and Indium(III) Chloride

Since chromanes are found in many natural products, efficient construction of this ring structure has attracted much attention. We have investigated indium-mediated intramolecular allylation and allenylation to carbonyl groups as well as imines and proved that these methods are efficient for constructing chromane ring structures. Recently, Araki and co-workers reported the transmetallation of π-allylpalladium(II) by an indium(I) salt and showed that allylation to carbonyl groups could be achieved by the resulting organoindium species. This process appears to involve a πallylpalladium(II) species which was, then, transmetallated with an indium salt. As a result, an allylindium reagent was generated, which is believed to be the active organometallic species to undergo allylation. Also, a very similar allylation using In, InCl3, and catalytic Pd(0) to carbonyl groups was also reported by Kim and co-workers. The actual active species involved for transmetallation in this process was also believed to be InCl, which was formed by the reaction of indium and indium(III) chloride. Interestingly, other metal chloride salts with higher reduction potential than In(I) can be utilized in the allylation reactions. Thus, SnCl4, FeCl3, or CuCl paired with indium metal in the presence of Pd(0) was successfully employed in the allylation with various allylic compounds. More recently, Araki and co-workers reported preparation of allylic indium from allylic alcohols via πallylnickel with InI. Allylindiums generated by abovementioned reductive transmetallation of π-allylpalladium(II) complexes were also used in allyl cross-coupling reactions. Because these methods seem to be efficient in allylation in intermolecular fashion, it is natural to consider possibility of applying these to intramolecular allylations. In connection with our continuing efforts to develop more efficient methods to synthesize chromane and chromane-related ring structures using organoindium species, we decided to investigate the allylation involving In, InCl3, and Pd(0) species to prepare chromane derivatives. Here we wish to disclose the results of our investigation on acquiring chromane and the related structures via an organoindium species generated by the transmetallation of π-allylpalladium(II) according to the allylation method reported by Kim and co-workers. First, we have focused our investigation on the construction of chromanes which possess 6-membered rings by the intramolecular allylation under the conditions involving In and InCl3 in the presence of Pd(PPh3)4 (Eq. 1).

Highly Efficient Allyl Cross‐Coupling Reactions of Allylindiums with Organic Electrophiles.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Highly efficient allyl cross-coupling reactions of allylindiums with organic electrophiles.

This paper describes highly efficient allyl cross-coupling reactions of allylindiums with organic electrophiles such as aryl and vinyl triflates, vinyl halides, dibromoolefin, and alkynyl iodide. The reactions were carried out using 4 mol % Pd(PPh3)4 in the presence of 3 equiv of LiCl in DMF at 100 degrees C under a nitrogen atmosphere. Allylindium, generated from the reaction of 1 equiv of indium with 1.5 equiv of allyl halide, gave the best result as a coupling partner. The present method is mild and simple to apply, and it produces a diverse range of allylic compounds in good to excellent yields.