Copper-Catalyzed Dehydrogenative Diels–Alder Reaction

Jiang, Bing; Liang, Qiuju; Han, Yuling; Zhao, Meng; Xu, Yun‐He; Loh, Teck‐Peng

doi:10.1021/acs.orglett.8b01067

Cited by 27 publications

(13 citation statements)

References 91 publications

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“…Systems such as the TM coordination complexes, 47−55 TM-exchanged clays, 52 and TM-exchanged zeolites 51 have been used earlier to catalyze DAC reactions. Among others, 50,54,56 catalytic systems based on Cu(I), 54,56 Cu(II), 56,57 Ni(II), 47,56 Zn(II), 47,56 Sc(III), 47,51,55 and Cr(III) 52,53,56 have been investigated. Typically, the reaction starts with a η 2 /η 4 -type coordination of the dienophile/diene to the metal ion.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Insight into the [4 + 2] Diels–Alder Cycloaddition over First Row d-Block Cation-Exchanged Faujasites

et al. 2018

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The Diels–Alder cycloaddition (DAC) is a powerful tool to construct C–C bonds. The DAC reaction can be accelerated in several ways, one of which is reactant confinement as observed in supramolecular complexes and Diels–Alderases. Another method is altering the frontier molecular orbitals (FMOs) of the reactants by using homogeneous transition-metal complexes whose active sites exhibit d-orbitals suitable for net-bonding orbital interactions with the substrates. Both features can be combined in first row d-block (TM) exchanged faujasite catalysts where the zeolite framework acts as a stabilizing ligand for the active site while confining the reactants. Herein, we report on a mechanistic and periodic DFT study on TM-(Cu(I), Cu(II), Zn(II), Ni(II), Cr(III), Sc(III), V(V))exchanged faujasites to elucidate the effect of d-shell filling on the DAC reaction between 2,5-dimethylfuran and ethylene. Two pathways were found: one being the concerted one-step and the other being the stepwise two-step pathway. A decrease in d-shell filling results in a concomitant increase in reactant activation as evidenced by increasingly narrow energy gaps and lower activation barriers. For models holding relatively small d-block cations, the zeolite framework was found to bias the DAC reaction toward an asynchronous one-step pathway instead of the two-step pathway. This work is an example of how the active site properties and the surrounding chemical environment influence the reaction mechanism of chemical transformations.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Insight into the [4 + 2] Diels–Alder Cycloaddition over First Row d-Block Cation-Exchanged Faujasites

et al. 2018

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“…HSiPh 3 , HSiPh 2 Me, HSiPhMe 2 , HSiBnMe 2 , HSi(OEt) 3 , HSiEt 3 , diallyl ether, and dienes 3a , 3b , 3m , 3n , 3o , and 3p were purchased from TCI or Aldrich. The mono(phosphine)palladium(0) complexes Pd{η 2 :η 2 -(CH 2 CHCH 2 ) 2 O}(PR 3 ) (R = Me ( 1a ), Et ( 1b ), Cy ( 1c ), OEt ( 1d ), O i Pr ( 1e ), Ph ( 1f ), OPh ( 1g )), , DSiPh 3 ( 2a - d ), HSiAr 3 (Ar = C 6 H 4 OMe-4 ( 2b ), C 6 H 4 Me-4 ( 2c ), C 6 H 4 Cl-4 ( 2d ), C 6 H 4 CF 3 -4 ( 2e )), and dienes 3c , 3d , 3e , 3f , 3g , 3h , 3i , 3j , 3k , 3l , and 3q were prepared by literature procedures with modification. 1 H, 2 H, and 13 C{ 1 H} NMR spectra were measured on a 400 MHz (for 1 H) NMR spectrometer.…”

Section: Experimental Sectionmentioning

confidence: 99%

Ligand-Controlled Regiodivergent Hydrosilylation of Conjugated Dienes Catalyzed by Mono(phosphine)palladium(0) Complexes

et al. 2020

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Mono(phosphine)palladium(0) complexes, [Pd(η2:η2-C6H10O)(PR3)] (1), catalyze hydrosilylation of electron-deficient conjugated dienes with HSiPh3. Hydrosilylation of methyl penta-2,4-dienoate with HSiPh3 catalyzed by [Pd(η2:η2-C6H10O)(PR3)] (R = Me (1a), Et (1b), OEt (1d), O i Pr (1e)) proceeds to give the 1,2-E product in quantitative yield with exclusive Markovnikov selectivity. In contrast, their triphenylphosphine and -phosphite analogues, [Pd(η2:η2-C6H10O)(PR3)] (R = Ph (1f), OPh (1g)), mainly produce the 1,4-Z product (1,2-E/1,4-Z = 3/7). The regioselectivity in the hydrosilylation of methyl 2,4-pentadienoate is also controlled by organosilanes. Mechanistic studies suggest that the reaction using a compact and basic mono-phosphorus complex proceeds by the Chalk–Harrod mechanism involving the reductive elimination from an (η3-allyl)(silyl)palladium(II). A poor electron-donating mono-phosphorus ligand such as P(OPh)3 destabilizes a Pd(II) species and promotes direct reductive elimination to give the 1,4-Z product. On the other hand, a compact and electron-donating phosphorus ligand, such as PMe3, PEt3, and P(OMe)3, favors to give the more stable (η3-allyl)(silyl)palladium(II) intermediate by the allyl rotation, followed by reductive elimination to give the 1,2-E product.

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“…[2] Chiral metal complexes have been widely used as catalysts for Aza Diels Alder reaction. [3][4][5] They are used for the synthesis of heterocyclic compounds containing six membered rings. Organic reactions utilizing α-amino acids as chiral source are more prevalent in asymmetric synthesis.…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Aza‐Diels Alder reaction catalyzed by clay supported Schiff base complex^†

Kannan¹,

Sreekumar

2020

Journal of Heterocyclic Chem

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Clay supported catalysts based on 2‐ hydroxy naphthaldehyde and amino acids, their copper and titanium complexes have been described. The catalysts were found to be active toward the synthesis of pyrano‐, furanoquinolines through Aza‐Diels Alder reaction. The catalysts gave good yield and high enantioselectivity. The catalysts were environmentally friendly, economical, synthetically robust and reusable.

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Copper-Catalyzed Dehydrogenative Diels–Alder Reaction

Cited by 27 publications

References 91 publications

Mechanistic Insight into the [4 + 2] Diels–Alder Cycloaddition over First Row d-Block Cation-Exchanged Faujasites

Mechanistic Insight into the [4 + 2] Diels–Alder Cycloaddition over First Row d-Block Cation-Exchanged Faujasites

Ligand-Controlled Regiodivergent Hydrosilylation of Conjugated Dienes Catalyzed by Mono(phosphine)palladium(0) Complexes

Enantioselective Aza‐Diels Alder reaction catalyzed by clay supported Schiff base complex^†

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Copper-Catalyzed Dehydrogenative Diels–Alder Reaction

Cited by 27 publications

References 91 publications

Mechanistic Insight into the [4 + 2] Diels–Alder Cycloaddition over First Row d-Block Cation-Exchanged Faujasites

Mechanistic Insight into the [4 + 2] Diels–Alder Cycloaddition over First Row d-Block Cation-Exchanged Faujasites

Ligand-Controlled Regiodivergent Hydrosilylation of Conjugated Dienes Catalyzed by Mono(phosphine)palladium(0) Complexes

Enantioselective Aza‐Diels Alder reaction catalyzed by clay supported Schiff base complex†

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Enantioselective Aza‐Diels Alder reaction catalyzed by clay supported Schiff base complex^†