Oxidative addition of allyl acetate to palladium(0) complexes

Yamamoto, Takakazu; Saitô, Osamu; Yamamoto, Akio

doi:10.1021/ja00408a068

Cited by 85 publications

(38 citation statements)

References 2 publications

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“…Thus, the initial complexes formed from crotyl or cinnamyl substrates will have the substituent on the allyl moiety and the ligand in a cis relationship (see Scheme 5). [50][51][52][53] Since in the NMR spectra only the syn,trans complexes (b) are observed (vide infra), we conclude that this is the most stable complex geometry. Therefore, the initially formed syn,cis complexes a will isomerise to the corresponding trans complex, by means of a pseudorotation mechanism.…”

Section: Allylic Alkylation Reactionsmentioning

confidence: 75%

“…Such relationships have been shown to give important information on the nature of the catalytically active species as bis-ligand complexes often show nonlinear effects. [52,53] The results for ligand 2 b are shown in Figure 1. Within experimental error, the stereochemical outcome of the reaction is linearly correlated to the ee of the ligand.…”

Section: Allylic Alkylation Reactionsmentioning

confidence: 99%

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Bulky Monodentate Phosphoramidites in Palladium‐Catalyzed Allylic Alkylation Reactions: Aspects of Regioselectivity and Enantioselectivity

Boele

Kamer

Lutz³

et al. 2004

Chemistry A European J

111

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A series of bulky monodentate phosphoramidite ligands, based on biphenol, BINOL and TADDOL backbones, have been employed in the Pd‐catalysed allylic alkylation reaction. Reaction of disodium diethyl 2‐methyl malonate with monosubstituted allylic substrates in the presence of palladium complexes of the phosphoramidite ligands proceeds smoothly at room temperature. The regioselectivities observed depend strongly on the leaving group and the geometry of the allylic starting compounds. Mono‐coordination occurs when these ligands are ligated in [Pd(allyl)(X)] complexes (allyl=C3H5, 1‐CH3C3H4, 1‐C6H5C3H4, 1,3‐(C6H5)2C3H3; X=Cl, OAc). The solid‐state structure determined by X‐ray diffraction of [Pd(C3H5)(1)(Cl)] reveals a non‐symmetric coordination of the allyl moiety, caused by the stronger trans influence of the phosphoramidite ligand relative to X−. In all of these complexes, the syn,trans isomer is the major species present in solution. Because of fast isomerisation and high reactivity of the syn,cis complex, the major product formed upon alkylation is the linear product, especially for monosubstituted phenylallyl substrates in the presence of halide counterions. In the case of biphenol‐ and BINOL‐based phosphoramidites, however, a strong memory effect is observed when 1‐phenyl‐2‐propenyl acetate is employed as the substrate. In this case, nucleophilic attack competes effectively with the isomerisation of the transient cinnamylpalladium complexes. The asymmetric allylic alkylation of 1,3‐diphenyl‐2‐propenyl acetate afforded the chiral product in up to 93 % ee. Substrates with smaller substituents gave lower enantioselectivities. The observed stereoselectivity is explained in terms of a preferential rotation mechanism, in which the product is formed by attack on one of the isomers of the intermediate [Pd{1,3‐(C6H5)2C3H3}(L)(OAc)] complex.

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Section: Allylic Alkylation Reactionsmentioning

confidence: 75%

Section: Allylic Alkylation Reactionsmentioning

confidence: 99%

Bulky Monodentate Phosphoramidites in Palladium‐Catalyzed Allylic Alkylation Reactions: Aspects of Regioselectivity and Enantioselectivity

Boele

Kamer

Lutz³

et al. 2004

Chemistry A European J

111

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“…This accelerating effect on the oxidative addition had already been demonstrated in the context of the formation of h 3 -allyl palladium complexes. [112] Particularly useful for the activation of aryl chlorides are palladium complexes of the bulky phosphane P(tBu) 3 , [113][114][115][116][117] which is readily available. [118] Even bulkier phosphanes, such as P(1-Ad)tBu 2 (Ad = adamantyl), have also been used in the palladium-catalyzed arylation of malonates and cyanoesters.…”

Section: Cross-coupling Reactions In the Presence Of Bulky Phosphanesmentioning

confidence: 99%

The Mechanisms of the Stille Reaction

2004

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Eighteen years ago in Angewandte Chemie John K. Stille reviewed a novel methodology, which eventually became known by his name, for the coupling of organostannanes with organic electrophiles. Since then that seed has blossomed into a multifaceted methodology full of hidden possibilities to explore, discover, and enjoy. Very recent modifications are making synthetic wishes come true that were only dreamed of a few years ago. Moreover, as important advances are being made in the understanding of the mechanistic details of the process, it is becoming increasingly possible to apply this essential reaction and its new variants in a less empirical way. The purpose of this Review is to give a critical account of this progress.

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“…Instead, we believe that reversible attack of acetate at the η 3 -allyl moiety (18) occurs in the absence of benzoquinone to form the (unobservable) Pd 0 (allyl acetate) species 4 (Scheme 5). Such a route is suggested by the reaction between allyl acetate and 2 in CD 3 COOD, which generates…”

mentioning

confidence: 99%

Mechanistic investigations of bipyrimidine-promoted palladium-catalyzed allylic acetoxylation of olefins

Lin¹,

Labinger²,

Bercaw³

2009

Can. J. Chem.

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Several pyridine-like ligands were found to improve Pd(OAc) 2 -catalyzed allylic oxidation of allylbenzene to cinnamyl acetate by p-benzoquinone in acetic acid. The best ligand examined, bipyrimidine, was used to identify the catalyst precursor for this system, (bipyrimidine)Pd(OAc) 2 , which was fully characterized. Mechanistic studies suggest the reaction takes place through disproportionation of (bipyrimidine)Pd(OAc) 2 to form a bipyrimidine-bridged dimer, which reacts with olefin to form a Pd II -olefin adduct, followed by allylic C-H activation to produce (η 3 -allyl)Pd II species. The (η 3 -allyl)Pd II intermediate undergoes a reversible acetate attack to generate a Pd 0 -(allyl acetate) adduct, which subsequently reacts with p-benzoquinone to release allyl acetate and regenerate (bipyrimidine)Pd(OAc) 2 . No KIE is observed for the competition experiment between allylbenzene-d 0 and allylbenzene-d 5 (CD 2 =CDCD 2 C 6 H 5 ), suggesting that allylic C-H activation is not rate-determining. Catalytic allylic acetoxylations of other terminal olefins as well as cyclohexene were also effected by (bipyrimidine)Pd(OAc) 2 .Key words: olefin, palladium catalysis, allylic C-H oxidation, p-benzoquinone, bipyrimidine.Résumé : On a observé que plusieurs ligands apparentés à la pyridine améliorent l'oxydation allylique de l'allylbenzène en acétate de cinnamyle par la p-benzoquinone dans l'acide acétique et catalysée par le Pd(OAc) 2 . On a utilisé le meilleur ligand étudié, la bipyrimidine, pour identifier le précurseur du catalyseur pour ce système, le (bipyrimidine)Pd(OAc) 2 , qui a été complètement caractérisé. Des études mécanistiques suggèrent que la réaction se produit par le biais d'une réaction de dismutation du (bipyrimidine)Pd(OAc) 2 qui conduit à la formation d'un dimère à pont bipyrimidine qui réagit avec l'oléfine pour conduire à un adduit Pd(II)-oléfine, le tout suivi de l'activation du C-H allylique conduisant à la formation de l'espèce (η 3 -allyl)Pd(II). L'intermédiaire (η 3 -allyl)Pd(II) subit une attaque réversible par l'ion acétate qui génère un adduit Pd°-(acétate d'allyle) qui réagit subséquemment avec la p-benzoquinone pour libérer l'acétate d'allyle et régénérer le (bipyrimidine)Pd(OAc) 2 . On n'observe aucun effet isotopique cinétique pour l'expérience de compétition entre l'allylbenzène-d 0 et l'allylbenzène-d 5 (CD 2 =CDCD 2 C 6 H 5 ); ce résultat suggère que l'activation allylique n'est pas l'étape cinétiquement déterminante. Les acétoxylations allyliques catalytiques du cyclohexène et d'autres oléfines terminales sont aussi affectées par le (bipyrimidine)Pd(OAc) 2 .

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Oxidative addition of allyl acetate to palladium(0) complexes

Cited by 85 publications

References 2 publications

Bulky Monodentate Phosphoramidites in Palladium‐Catalyzed Allylic Alkylation Reactions: Aspects of Regioselectivity and Enantioselectivity

Bulky Monodentate Phosphoramidites in Palladium‐Catalyzed Allylic Alkylation Reactions: Aspects of Regioselectivity and Enantioselectivity

The Mechanisms of the Stille Reaction

Mechanistic investigations of bipyrimidine-promoted palladium-catalyzed allylic acetoxylation of olefins

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