Stereochemistry of nucleophilic attack on π-allylpalladium complexes. Evidence for cis-migration of acetate from palladium to carbon

Bäckvall, Jan‐E.; Nordberg, Ruth E.; Björkman, Eva; Moberg, Christina

doi:10.1039/c39800000943

Cited by 58 publications

(27 citation statements)

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“…No reaction occurred under a nitrogen atmosphere (entry 14). Finally, isopropyl alcohol was proven to be superior to other alcohols, such as methanol, n-propanol and benzyl alcohol (entries [15][16][17]. It is also worth noting that no reaction was observed in toluene (entry 18).…”

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confidence: 98%

“…Alkenes with electron-withdrawing groups [16] were tested as additives in this reaction; maleic anhydride (MA, 20 mol %) was found to give better result (67 %, entry 9) than other additives, such as benzoquinone (BQ) and 1,4-naphthoquinone (NQ) (entries 10 and 11). Lower substrate concentration seemed beneficial to this reaction: the reaction of 1 a gave the best yield (83 %) when the reaction was conducted in a 0.05 m solution of isopropyl alcohol (entry 12).…”

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confidence: 99%

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Palladium‐Catalyzed Intramolecular Hydroamination of Allenes Coupled to Aerobic Alcohol Oxidation

Qiu

Wei

Liu

2009

Chemistry A European J

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confidence: 98%

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confidence: 99%

Palladium‐Catalyzed Intramolecular Hydroamination of Allenes Coupled to Aerobic Alcohol Oxidation

Qiu

Wei

Liu

2009

Chemistry A European J

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“…These results are consistent with a mechanism involving p-allylpalladium intermediates and suggest that maleic anhydride facilitates nucleophilic attack on the pallylpalladium species. [16] In conclusion, we have developed a novel method for the highly regioselective synthesis of linear (E)-allylimide from palladium-catalyzed oxidative amination of unactivated alkyl olefins, and the catalytic system allows an efficient dioxygencoupled turnover without additional redox-active cocatalysts. Investigation of the reaction mechanism is in progress.…”

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confidence: 99%

Palladium‐Catalyzed Intermolecular Aerobic Oxidative Amination of Terminal Alkenes: Efficient Synthesis of Linear Allylamine Derivatives

2008

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Dedicated to Professor Xiyan Lu on the occasion of his 80th birthdayThe rich variety of nitrogen-containing molecules that occur as natural and synthetic products has inspired considerable interest in the development of new methods for their syntheses.[1] Among the strategies involving the direct amination of olefins by CÀN bond formation, [2][3] the synthesis of amine derivatives by intermolecular dioxygen-coupled oxidative amination of olefins is particularly attractive. [4][5][6] Palladium-catalyzed methods for intermolecular aerobic oxidative amination of unactivated olefins, known as azaWacker reactions, have been recently reported to yield enamide derivatives (Scheme 1, left arrow).[2e, 4, 6] These reactions are proposed to proceed by Markovnikov aminopalladation of the alkene with subsequent bhydride elimination, resulting in the functionalization of the olefin at the C2 position. Herein we describe a new method for intermolecular dioxygen-coupled oxidative amination of unactivated olefins under cocatalyst free reaction conditions, which affords linear allylic amine derivatives with high regioselectivity (Scheme 1, right arrow). [7][8][9][10] These reactions appear to proceed by allylic CÀH activation and subsequent nucleophilic attack at the C1 position of an intermediate pallylpalladium species. We initiated the search for allylic amination reactions by examining the reaction of 1-undecene (1 a) with nitrogen nucleophiles having an acidic NH group.[11] Dimethylacetamide (DMA) was selected as the solvent because it was shown to be the most effective solvent for aerobic allylic acetoxylation of alkenes.[7c] Treatment of phthalimide and 1 a with Pd(OAc) 2 under a dioxygen atmosphere (6 atm) in the presence or absence of the basic resin D301 (OH) [12] afforded oxidative amination products exclusively associated with azaWacker-type reactivity; the products were enimide 3 and various alkene isomers (Scheme 2). No allylic amination products were observed. The reaction of tosylamide and Nmethyl tosylamide did not form any amination product. The use of saccharin as the nucleophile, however, resulted in highly regioselective linear (E)-allylic amination products (2) and the corresponding alkene isomers (Scheme 2). Optimal results were obtained when the reaction was performed in the presence of maleic anhydride (MA) and 4 molecular sieves (see the Supporting Information Table-S1 for details), which led to a 95 % yield of the oxidative allylic amination product with respect to saccharin. Only linear amination products (C1 amination) were obtained; neither the enimide (C2 amination) nor the branched allylimide (C3 amination) was detected. The yield decreased to 78 % under 1 atmosphere of dioxygen, and the use of N-methylpyrrolidinone (NMP) or N,N-dimethylformamide (DMF) instead of DMA, gave a slightly lower yield. A very low product yield (ca. 10 %) was obtained with dimethylsulfoxide (DMSO) as the solvent. Scheme 2. Pd-catalyzed the aerobic oxidative amination of 1-undecene (1 a) with phthalimide and saccharin.

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“…Complexes of type I in Scheme 1 (R ϭ Ph, Bz) are well amount of [Pd(SPh) 2 (dppe)] (6a) was formed. They were isolated as pale yellow powdery/microcrystalline substances and fully characterized by 13 C and 31 P NMR spectroscopy. Furthermore, complex 3b was found to react in THF with disulfides RЈSSRЈ (RЈ = Ph, Bz, Me), yielding [Pd(CH 2 CH 2 CH 2 Ph)(SRЈ)(dppe)] (RЈ = Ph, 5b; Bz, 5f, Me, 5g) with small amounts (3−13%) of [Pd(SRЈ) 2 (dppe)] (6) as side products.…”

Section: Introductionmentioning

confidence: 99%

“…[10] Only a few of these complexes could be structurally characterized, namely trans-[PdEt(X)(PMe 3 Palladium complexes with acyclic β-hydrogen-containing alkyl ligands cover a wide range of stability: PdEtI without supporting ligands already decompose at Ϫ100°C [11] whereas toluene solutions of complexes with dithiocarbamato [7] and tris(pyrazolyl)borate [10d] co-ligands were found to be stable to 60°C and to at least 80°C, respectively. [13] Furthermore, complexes with CH 2 ϪCH 2 Ph and CHPhϪCH 2 Ph ligands were detected by NMR spectroscopy as intermediates in reactions of phenylpalladium complexes with ethene and styrene, respectively. Preferred decomposition pathways are β-hydrogen elimination and/or reductive elimination in the case of dialkyl complexes.…”

Section: Introductionmentioning

confidence: 99%

(Phenylalkyl)palladium Complexes Containing β-Hydrogen Atoms: Synthesis and Characterization of [PdR2(dppe)], [PdR(SPh)(dppe)] (R = CH2CH2Ph, CH2CH2CH2Ph, CH2CHMePh), and [Pd(CH2CH2CH2Ph)X(dppe)] (X = I, Br, Cl)

Spaniel

Schmidt

Wagner

et al. 2002

Eur. J. Inorg. Chem.

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Reactions of HgR 2 (R = CH 2 CH 2 Ph, 1a; CH 2 CH 2 CH 2 Ph, 1b; CH 2 CHMePh, 1c) (prepared from HgCl 2 and the requisite Grignard compounds) with lithium in toluene afforded (phenylalkyl)lithium compounds LiR (2a−c) in yields of between 64 and 81%. At −30°C, they react with [PdCl 2 (dppe)] [dppe = 1,2-bis(diphenylphosphanyl)ethane] yielding bis-(phenylalkyl)palladium(II) complexes [PdR 2 (dppe)] (3a−c) which were isolated (T dec = 159°C, 3a; 80°C, 3b; 145°C, 3c) and fully characterized by 1 H, 13 C, and 31 P NMR spectroscopy.Single-crystal X-ray diffraction of [Pd(CH 2 CH 2 Ph) 2 (dppe)] (3a) showed that the palladium atom is square-planar coordinated by two 2-phenylethyl ligands and the dppe ligand. The two CH 2 CH 2 Ph ligands exhibite nearly a fully staggered conformation. Overall, a good approximation for the complex is that it has C 2 symmetry with the C 2 axis defined by the Pd atom and the midpoint of the central C−C bond of the dppe ligand. Bis(phenylalkyl)palladium complexes 3a and 3b reacted with PhSH in a 1:1 ratio yielding [PdR(SPh)(dppe)] (R = CH 2 CH 2 Ph, 5a; CH 2 CH 2 CH 2 Ph, 5b), whereas in the case of complex 3c, besides [Pd(CH 2 CHMePh)(SPh)(dppe)] (5c), a considerable [a]

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Stereochemistry of nucleophilic attack on π-allylpalladium complexes. Evidence for cis-migration of acetate from palladium to carbon

Cited by 58 publications

References 0 publications

Palladium‐Catalyzed Intramolecular Hydroamination of Allenes Coupled to Aerobic Alcohol Oxidation

Palladium‐Catalyzed Intramolecular Hydroamination of Allenes Coupled to Aerobic Alcohol Oxidation

Palladium‐Catalyzed Intermolecular Aerobic Oxidative Amination of Terminal Alkenes: Efficient Synthesis of Linear Allylamine Derivatives

(Phenylalkyl)palladium Complexes Containing β-Hydrogen Atoms: Synthesis and Characterization of [PdR2(dppe)], [PdR(SPh)(dppe)] (R = CH2CH2Ph, CH2CH2CH2Ph, CH2CHMePh), and [Pd(CH2CH2CH2Ph)X(dppe)] (X = I, Br, Cl)

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