Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction

Yu, Jie; Jiang, Hua‐Jie; Zhou, Ya; Luo, Sanzhong; Gong, Liu‐Zhu

doi:10.1002/anie.201504790

Cited by 116 publications

(48 citation statements)

References 62 publications

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“…[1] Benefiting from the renaissance of visible-light-induced organic photochemistry, which delivers adiverse variety of radical intermediates in an environment-and user-friendly means, [2] exciting developments of catalytic asymmetric radical transformations have been witnessed in the past decade. [5,6] Despite great contributions having been made in this field, exploring chiral octahedral complexes avoiding precious metals and allowing facile steric regulation is still highly desirable. [5,6] Despite great contributions having been made in this field, exploring chiral octahedral complexes avoiding precious metals and allowing facile steric regulation is still highly desirable.…”

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confidence: 99%

“…[3,4] Thesearch for efficient chiral catalysts and concepts that are compatible with photochemical processes is obliviously crucial to this notable success.I nt his respect, the Meggers group successfully developed Ir-, Rh-, and Ru-based chiral octahedral complexes, [4] which have impressive catalytic efficiency and stereoinduction capacity in as eries of visible-light-induced asymmetric radical reactions.M ore significantly,t he concept of octahedral metal-centered chirality provided an important cornerstone for steering the development of new chiral organometallic catalysts. [6] Given the excellent stereoinduction of chiral N 4 ligands in asymmetric oxidations by joint use with Fe and Mn salts, [7] here we designed ak ind of novel chiral Co-centered octahedral complexes under the guidance of Meggers concept ( Figure 1a). [6] Given the excellent stereoinduction of chiral N 4 ligands in asymmetric oxidations by joint use with Fe and Mn salts, [7] here we designed ak ind of novel chiral Co-centered octahedral complexes under the guidance of Meggers concept ( Figure 1a).…”

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Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

et al. 2019

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Chiral catalysts tolerating photochemical reactions are in great demand for the vast development of visible-lightinduced asymmetric synthesis.N ow,c hiral octahedral complexes based on earth-abundant metal and chiral N 4 ligands are reported. One well-defined chiral Co II -complex is shown to be an efficient catalyst in the visible-light-induced conjugated addition of enones by alkyl and acyl radicals,p roviding synthetically valued chiral ketones and 1,4-dicarbonyls in 47-> 99 %yields with up to 97:3 e.r.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

et al. 2019

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“…[3,4] Thesearch for efficient chiral catalysts and concepts that are compatible with photochemical processes is obliviously crucial to this notable success.I nt his respect, the Meggers group successfully developed Ir-, Rh-, and Ru-based chiral octahedral complexes, [4] which have impressive catalytic efficiency and stereoinduction capacity in as eries of visible-light-induced asymmetric radical reactions.M ore significantly,t he concept of octahedral metal-centered chirality provided an important cornerstone for steering the development of new chiral organometallic catalysts. [5,6] Despite great contributions having been made in this field, exploring chiral octahedral complexes avoiding precious metals and allowing facile steric regulation is still highly desirable. [6] Given the excellent stereoinduction of chiral N 4 ligands in asymmetric oxidations by joint use with Fe and Mn salts, [7] here we designed ak ind of novel chiral Co-centered octahedral complexes under the guidance of Meggers concept ( Figure 1a).…”

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confidence: 99%

Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

Zhang

Jia

et al. 2019

Angewandte Chemie

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“…Kinetic studies revealed that optically pure CCC À Na + showed ah igher catalytic activity than ar acemic catalyst sample ( Figure S2), [9] which might be the possible reason for the positive nonlinear effect. [10] According to these experimental data and the crystal structures of CCC À Na + L-4h [11] and the products 3aa and 3ia, [12] we propose at ransition state to explain the observed stereochemistry (Scheme 2). Thes odium cation, in combination with the weakly coordinating chiral anion, is considered to act as aLewis acid to activate 2-azadiene 1a,leading to the possible transition state TS-I,a ss uggested by preliminary DFT calculations.…”

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confidence: 74%

Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction

Jiang

Zhou

et al. 2015

Angewandte Chemie

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The sodium salts of anionic chiral cobalt(III) complexes (CCC À Na + )h ave been found to be efficient catalysts of the asymmetric Povarov reaction of easily accessible dienophiles,s uch as 2,3-dihydrofuran, ethyl vinyl ether, and an N-protected 2,3-dihydropyrrole,w ith 2-azadienes. Ring-fused tetrahydroquinolines with up to three contiguous stereogenic centers were thus obtained in high yields,excellent diastereoselectivities (endo/exo up to > 20:1), and high enantioselectivities (up to 95:5 e.r.).The use of chiral anions as stereoinductors in the field of asymmetric catalysis has received increasing attention. [1] Whereas organic molecular anion catalysts have been widely employed, the potential of chiral metal complexes as counteranions in asymmetric catalysis has hardly been explored. Belokon et al. recently showed that salicylaldehyde-derived chiral Co III complexes can be employed to accelerate afew CÀCbond formation reactions by asymmetric counterion catalysis.[2b-d] However,t hese transformations proceeded with low to moderate enantioselectivities [2a-d] owing to the limitations of unsubstituted salicylaldehydes and the meridional stereoisomers of these complexes.[2e-f] We envisioned that easily prepared, structurally tunable,a nd stereochemically stable [2g] metal salts of anionic chiral Co III complexes (CCC À M + )that are derived from salicylaldehydes with bulky substituents and l-amino acids would be more applicable to asymmetric catalysis than anticipated by common sense (Scheme 1). We hypothesized that the achiral cation can activate as ubstrate while the chiral counteranion might be applied to control the stereoselectivity of the transformation. Thus,wedecided to test these catalysts in the challenging Povarov reaction [3] of simple 2-azadienes and dienophiles to generate structurally diverse 1,2,3,4-tetrahydroquinoline (THQ) derivatives with contiguous stereogenic centers,w hich are key structural motifs of numerous natural products and pharmacologically relevant molecules. [4] Thec atalytic enantioselective Povarov reaction has been intensively investigated [5][6][7] since the pioneering work by Ishitani and Kobayashi, who employed ac hiral ytterbium complex as the catalyst.[6a] In these cases,classical chiral Lewis acids [6] or chiral Brønsted acids [7] have generally been the catalysts of choice to promote asymmetric versions.Thus,the development of new chiral catalyst motifs that are principally distinct from traditional ones is still highly desirable.Herein, we show that the sodium salts of anionic chiral Co III complexes (CCC À Na + )a re able to act as promising chiral catalysts for the asymmetric Povarov reaction of aw ide variety of simple 2-azadienes and dienophiles,s uch as 2,3-dihydrofuran, ethyl vinyl ether, and an N-protected 2,3-dihydropyrrole,g iving rise to multiply substituted THQ derivatives in high yields and with excellent stereoselectivities (Scheme 1).Our initial investigation started with the reaction of N-phenyl benzaldimine (1a)with 2,3-dihydrofuran (2a)int...

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Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction

Cited by 116 publications

References 62 publications

Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

Exploration of a Chiral Cobalt Catalyst for Visible‐Light‐Induced Enantioselective Radical Conjugate Addition

Sodium Salts of Anionic Chiral Cobalt(III) Complexes as Catalysts of the Enantioselective Povarov Reaction

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