Alkylation of allylic derivatives. 8. Regio- and stereochemistry of alkylation of allylic carboxylates with lithium methylcyanocuprate

Goering, Harlan L.; Kantner, Steven S.

doi:10.1021/jo00177a006

Cited by 70 publications

(13 citation statements)

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“…We finally applied these 6 NHC ligands to a copper-catalyzed allylic arylation of cinnamyl bromide with PhMgBr to evaluate the influence of the structure on catalytic activity. Mechanistically, a bulky and electron-deficient ligand is thought to be preferable because it heightens S N 2′ selectivity . Our group previously found that the DHASIMeCuCl complex, which forms in situ, generates S N 2′-substituted products as its major yield (S N 2:S N 2′ = 20:80), whereas IMeCuCl gave us a 1:1 mixture of S N 2 and S N 2′ substituted products.…”

Section: Resultsmentioning

confidence: 99%

Analyses of the Structural and Electronic Properties of NHCs with Bicyclic Architectures

2020

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Quantification of the steric and electronic properties of ligands is an important task for the development of highly effective chemical transformations when using a metal complex as a catalyst. In this study, we used silver and iridium complexes to perform systematic analyses to quantify the steric and electronic properties of original NHCs, which we refer to as DHASI and BCPSI. In addition to two silver chloride complexes that we previously reported, two novel BCPSIiPrAgCl and BCPSICyAgCl complexes were prepared and used for XRD studies to quantify the steric properties via use of a method referred to as the percent buried volume (%V Bur ). We then synthesized 6 IrCl(CO) 2 (HNC) complexes to calculate the TEP values, and the results indicated that the influences of two different core bicyclic motifs were somewhat unclear, while the influences of different N-substituents were readily apparent. Finally, the original NHCs were applied to a copper catalyzed allylic arylation of cinnamyl bromide with PhMgBr. The regioselectivity of the substitutions suggested that the steric environments existing at relatively long distances from the bound copper also exerted a considerable amount of influence over the catalytic properties.

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Section: Resultsmentioning

confidence: 99%

Analyses of the Structural and Electronic Properties of NHCs with Bicyclic Architectures

2020

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“…[4] Notably, no significant differences were seen between runs using preformed complex 6 and tests carried out with the catalyst obtained from 1 in situ (entries 1 and 2); this observation justified the use of catalysts generated in situ. [4,6,[20][21][22][23][24][25][26][27][28] In these two possible pathways, a bulky ligand should accelerate the reductive elimination step leading to the γ-product. The proportion of branched product increased in the order 1Ͻ 2 Ͻ 3 Ͻ 4, with the b/l ratios varying from 22:78 for 1 to 78:22 for 4 (entries 1-4).…”

Section: Resultsmentioning

confidence: 99%

“…[1][2][3] Being applicable to the formation of carbon-carbon, carbon-nitrogen, and carbon-oxygen bonds, it has become very popular in the field of natural product synthesis as well as in biomolecular and medicinal chemistry. Interestingly, allylic substitution with this particular metal arylated compounds in variable proportions, with the b/l ratio being the highest (78: 22) for the most crowded imidazolium salt used, namely that in which the second nitrogen atom (N2) was substituted by a mesityl group. The nucleophilic attack can lead to two compounds, the S N 2-product (or α-product) or the S N 2Јproduct (or γ-product), with regiocontrol of the reaction depending on various factors, such as the leaving group, the nature of the solvent, and the catalytic ligand-metal combination.…”

Section: Introductionmentioning

confidence: 96%

Copper‐Catalysed Allylic Substitution Using 2,8,14,20‐Tetrapentylresorcinarenyl‐Substituted Imidazolium Salts

et al. 2015

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International audienceUnsymmetrical imidazolium salts, each having one nitrogen atom (N1) substituted by a cavity-shaped TPR group (TPR = 2,8,14,20-tetrapentylresorcinaren-5-yl), were tested in situ as proligands for the copper-catalysed allylic arylation of cinnamyl bromide with arylmagnesium halides. The catalytic systems produced mixtures of linear (l) and branched (b) arylated compounds in variable proportions, with the b/l ratio being the highest (78:22) for the most crowded imidazolium salt used, namely that in which the second nitrogen atom (N2) was substituted by a mesityl group. An N-heterocyclic carbene complex obtained from one of the imidazolium salts was characterised by an X-ray diffraction stud

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“…This can be attributed to a back donation of the filled d 10 orbitals of the Cu atom into the s* orbital of the OPiv group, [39] the extent of which is determined by the nature of the leaving group and the steric resistance. [40][41][42][43] The dihedral angle of C2 À C1 À Cu À C4 is 173.68 in 3-O and 155.78 in 3, respectively. Clearly, this rotation of the dihedral angle can be attributed to the electrostatic attraction between the OPiv group and the Cu group.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of Copper(I)‐Catalyzed Allylic Alkylation of Phosphorothioate Esters: Influence of the Leaving Group on α Regioselectivity

Sheng

Wang

Lein

et al. 2013

Chemistry A European J

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The mechanism of Cu(I) -catalyzed allylic alkylation and the influence of the leaving groups (OPiv, SPiv, Cl, SPO(OiPr)2 ; Piv: pivavloyl) on the regioselectivity of the reaction have been explored by using density functional theory (DFT). A comprehensive comparison of many possible reaction pathways shows that [(iPr)2 Cu](-) prefers to bind first oxidatively to the double bond of the allylic substrate at the anti position with respect to the leaving group, and this is followed by dissociation of the leaving group. If the leaving group is not taken into account, the reaction then undergoes an isomerization and a reductive elimination process to give the α- or γ-selective product. If OPiv, SPiv, Cl, or SPO(OiPr)2 groups are present, the optimal route for the formation of both α- and γ-substituted products changes from the stepwise elimination to the direct process, in which the leaving group plays a stabilizing role for the reactant and destabilizes the transition state. The differences to the energy barrier for the α- and γ-substituted products are 2.75 kcal mol(-1) with SPO(OiPr)2 , 2.44 kcal mol(-1) with SPiv, 2.33 kcal mol(-1) with OPiv, and 1.98 kcal mol(-1) with Cl, respectively; these values show that α regioselectivity in the allylic alkylation follows a SPO(OiPr)2 >SPiv>OPiv>Cl trend, which is in satisfactory agreement with the experimental findings. This trend mainly originates in the differences between the attractive electrostatic forces and the repelling steric interactions of the SPO(OiPr)2 , SPiv, OPiv, and Cl groups on the Cu group.

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Alkylation of allylic derivatives. 8. Regio- and stereochemistry of alkylation of allylic carboxylates with lithium methylcyanocuprate

Cited by 70 publications

References 0 publications

Analyses of the Structural and Electronic Properties of NHCs with Bicyclic Architectures

Analyses of the Structural and Electronic Properties of NHCs with Bicyclic Architectures

Copper‐Catalysed Allylic Substitution Using 2,8,14,20‐Tetrapentylresorcinarenyl‐Substituted Imidazolium Salts

Mechanism of Copper(I)‐Catalyzed Allylic Alkylation of Phosphorothioate Esters: Influence of the Leaving Group on α Regioselectivity

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