Enantioselective synthesis of tetrahydroisoquinoline derivatives <i>via</i> chiral-at-metal rhodium complex catalyzed [3+2] cycloaddition

Qurban, Saira; Du, Yu; Gong, Jun; Lin, Shaoxia; Kang, Qiang

doi:10.1039/c8cc08275h

Cited by 29 publications

(13 citation statements)

References 51 publications

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“…Recently, an alternative to this modular chiral-ligand-plus-metal design has emerged in which chiral transition metal catalysts exclusively consist of achiral ligands. , In this approach, the essential overall chirality is the consequence of an asymmetric coordination of the achiral ligands around the central metal, thereby implementing metal-centered chirality (Figure b). Proof-of-principle for such chiral-at-metal catalysts has been demonstrated recently for the precious metals iridium, rhodium, , and ruthenium , by us and others, but the design of reactive chiral-at-metal catalysts based on earth-abundant metals, which have economical and environmental benefits, is elusive . This can be pinpointed to the much higher lability of coordinative bonds of 3d as compared to 4d and 5d transition metals, and it is an unresolved challenge to combine a configurationally inert metal stereocenter with a reactive metal center in a single transition metal catalyst.…”

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confidence: 99%

Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis

et al. 2019

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A new class of chiral iron catalysts is introduced that contains exclusively achiral ligands with the overall chirality being the result of a stereogenic iron center. Specifically, iron(II) is cis-coordinated to two N-(2-pyridyl)-substituted N-heterocyclic carbene (PyNHC) ligands in a bidentate fashion in addition to two monodentate acetonitriles, and the dicationic complex is complemented by two hexafluorophosphate ions. Depending on the helical twist of the PyNHC ligands, the metal center adopts either a Λ or Δ absolute configuration. Importantly, the two PyNHC ligands are constitutionally and configurationally inert, while the two acetonitriles are labile and allow asymmetric transition metal catalysis. This is demonstrated with an enantioselective Cannizzaro reaction (96% yield, 88% ee) and an asymmetric Nazarov cyclization (89% yield, >20:1 dr, 83% ee).

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Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis

et al. 2019

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“…This process reduces the amount of possible stereoisomers to two, which represents a significant enhancement of our previously reported synthetic protocol since it greatly facilitates the separation of the diastereomers and renders the preparation of this class of catalysts less time consuming. Thus, chiral BOX ligands are an economical tool for the synthesis of nonracemic bis-cyclometalated rhodium complexes, which have been used extensively over the past few years as chiral transition-metal catalysts. ,,, Further investigations addressing the generality of the introduced auxiliary-mediated approach for the asymmetric synthesis of chiral transition-metal catalysts different from rhodium are currently being pursued.…”

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confidence: 99%

Chiral Bis(oxazoline) Ligands as C₂-Symmetric Chiral Auxiliaries for the Synthesis of Enantiomerically Pure Bis-Cyclometalated Rhodium(III) Complexes

et al. 2019

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The synthesis of enantiomerically pure bis-cyclometalated rhodium(III) complexes using chiral bis(oxazoline) ligands as C 2 -symmetric chiral auxiliaries is described. Bis(oxazolines) are versatile chiral ligands for asymmetric catalysis but have not been applied to the resolution of racemic mixtures of transition-metal complexes. Due to their C 2 symmetry, chiral bis(oxazolines) are particularly useful for the synthesis of nonracemic transitionmetal complexes with lower symmetry, and this is demonstrated with the synthesis of an enantiomerically pure rhodium(III) complex containing two different cyclometalated ligands.

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“…Furthermore, a gram-scale synthesis yielding the product with high stereoselectivity used as low as 0.5 mol% catalyst (Scheme 15). 44 O Cl…”

Section: Scheme 14 Enantioselective [3+2] Cycloaddition Of Cn-cyclicmentioning

confidence: 99%

Asymmetric Synthesis of C1-Chiral THIQs with Imines in Isoquinoline Rings

Chen

Gao

2020

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Tetrahydroisoquinoline (THIQ) scaffolds are important structural units that widely exist in a variety of natural alkaloids and synthetic analogues. Asymmetric synthesis of C1-chiral THIQ is of particular importance due to its significant pharmaceutical, agrochemical, and other biological activities, and the usually distinct bioactivities exhibited by the two enantiomers. In this review, we highlight the significant advances achieved in this field, present recent asymmetric synthesis with imines in isoquinoline rings ordered according to the sequence of various substrate types. New strategies could be inspired and more types of substrates need further development.1 Introduction2 Catalytic Asymmetric Reaction of Dihydroisoquinolines2.1 Asymmetric Reactions of 3,4-Dihydroisoquinolines2.2 Asymmetric Reactions of Dihydroisoquinolinium Salts2.3 Asymmetric Reactions of C,N-Cyclic N′-Acyl Azomethine Imines2.3.1 NED [3+2] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.2 IED [3+2] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.3 [3+3] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.4 [4+3] Cycloaddition of C,N-Cyclic N′-Acyl Azomethine Imines2.3.5 Asymmetric Addition Reactions to C,N-Cyclic N′-Acyl Azomethine Imines2.4 Asymmetric Reactions of C,N-Cyclic Nitrones3 Catalytic Asymmetric Mannich Reactions of Isoquinolines4 Conclusions and Perspectives

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Enantioselective synthesis of tetrahydroisoquinoline derivatives via chiral-at-metal rhodium complex catalyzed [3+2] cycloaddition

Abstract: An asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with α,β-unsaturated 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium complex has been developed.

Cited by 29 publications

References 51 publications

Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis

Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis

Chiral Bis(oxazoline) Ligands as C₂-Symmetric Chiral Auxiliaries for the Synthesis of Enantiomerically Pure Bis-Cyclometalated Rhodium(III) Complexes

Asymmetric Synthesis of C1-Chiral THIQs with Imines in Isoquinoline Rings

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Enantioselective synthesis of tetrahydroisoquinoline derivatives via chiral-at-metal rhodium complex catalyzed [3+2] cycloaddition

Abstract: An asymmetric [3+2] cycloaddition of C,N-cyclic azomethine imines with α,β-unsaturated 2-acyl imidazoles catalyzed by a chiral-at-metal rhodium complex has been developed.

Cited by 29 publications

References 51 publications

Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis

Chiral-at-Iron Catalyst: Expanding the Chemical Space for Asymmetric Earth-Abundant Metal Catalysis

Chiral Bis(oxazoline) Ligands as C2-Symmetric Chiral Auxiliaries for the Synthesis of Enantiomerically Pure Bis-Cyclometalated Rhodium(III) Complexes

Asymmetric Synthesis of C1-Chiral THIQs with Imines in Isoquinoline Rings

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Chiral Bis(oxazoline) Ligands as C₂-Symmetric Chiral Auxiliaries for the Synthesis of Enantiomerically Pure Bis-Cyclometalated Rhodium(III) Complexes