Interaction of palladium(0) complexes with allylic acetates, allyl ethers, allyl phenyl chalcogenides, allylic alcohols, and allylamines.  Oxidative addition, condensation, disproportionation, and .pi.-complex formation

Yamamoto, Takakazu; Akimoto, Mitsuru; Saitô, Osamu; Yamamoto, Akio

doi:10.1021/om00139a009

Cited by 114 publications

(46 citation statements)

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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: 74%

“…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

110

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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: 74%

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

110

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“…[16] Using Pd(PCy 3 ) 2 as the palladium species, Yamamoto et al obtained diallyl ether and its coordination product [Equation (2)]. [18] According to the authors, the formation of Pd(diallyl ether)(PCy 3 ) occurs through a η 3 -allylpalladium complex (i.e., an oxidative addition of 1 to Pd(PCy 3 ) 2 , and its reaction with 1 either at the Pd atom or at the η 3 -allyl moiety as shown in Scheme 3). [19] According to Hosokawa et al, the (η 3 -allyl)palladium complex is obtained by addition of HPdCl to the double bond, β-OH elimination, and abstraction of an allylic hydrogen by the OH ligand (Scheme 4).…”

Section: Stoichiometric Formation Of η 3 -Allylpalladium Complexes Frmentioning

confidence: 99%

“…[41] The reaction was also efficient in acetone (96 % yield) and even in the absence of solvent (70-80 % yield). According to the authors, the promotion effect of CO 2 is due to the formation of the reactive allyl hydrogen carbonate (i.e., to the conversion of the OH moiety into a more labile leaving group; Scheme 10 Yamamoto's process is compatible with the use of morpholine [Equation (18)] and other alcohols (2-methylprop-2-en-1-ol, but-2-en-1-ol), but steric hindrance of the reagents resulted in a decrease in the yields. [41] Masuyama et al used overstoichiometric amounts of tin(II) chloride as the promoter; SnBr 2 was less effective while no reaction occurred with SnF 2 and Sn(OAc) 2 .…”

Section: -Catalyzed Allylations In the Presence Of Promotersmentioning

confidence: 99%

Procedures for and Possible Mechanisms of Pd‐Catalyzed Allylations of Primary and Secondary Amines with Allylic Alcohols

Мuzart

2007

Eur J Org Chem

166

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This review describes the different Pd‐catalyzed methods that afford allylic amines from intermolecular reactions between allylic alcohols and amines and, with personal comments, the mechanisms that have been proposed. Allylic amines are an important class of compounds, while a wide structural variety of allylic alcohols are commercially available and are abundant in nature. The advantages of the use of allylic alcohols over that of their derivatives such as allylic esters or carbonates are the high atom efficiency and the formation only of water as the by‐product. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

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“…The direct activation of allylic alcohols, without pre-activation of the alcohol moiety, in palladium catalyzed allylic substitution reactions for application in C-C and C-X bond formation, is of growing interest [1][2][3]. Traditionally, allylic alcohols are pre-activated by transforming the alcohol moiety into a better leaving group, such as a halide, tosylate, carboxylate or phosphate.…”

Section: Introductionmentioning

confidence: 99%

A Mechanistic Study of Direct Activation of Allylic Alcohols in Palladium Catalyzed Amination Reactions

2015

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Abstract:We here report a computational approach on the mechanism of allylicamination reactions using allyl-alcohols and amines as the substrates and phosphoramidite palladium catalyst 1a, which operates in the presence of catalytic amount of 1,3-diethylurea as a co-catalyst. DFT calculations showed a cooperative hydrogen-bonding array between the urea moiety and the hydroxyl group of the allyl alcohol, which strengthens the hydrogen bond between the O-H moiety of the coordinated allyl-alcohol and the carbonyl-moiety of the ligand. This hydrogen bond pattern facilitates the (rate-limiting) C-O oxidative addition step and leads to lower energy isomers throughout the catalytic cycle, clarifying the role of the urea-moiety.

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Interaction of palladium(0) complexes with allylic acetates, allyl ethers, allyl phenyl chalcogenides, allylic alcohols, and allylamines. Oxidative addition, condensation, disproportionation, and .pi.-complex formation

Cited by 114 publications

References 0 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

Procedures for and Possible Mechanisms of Pd‐Catalyzed Allylations of Primary and Secondary Amines with Allylic Alcohols

A Mechanistic Study of Direct Activation of Allylic Alcohols in Palladium Catalyzed Amination Reactions

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