Iridium-Catalyzed Asymmetric Allylic Substitution Reactions

Chemical Reviews, Journal Year: 2018, Volume and Issue: 119(3), P. 1855 - 1969

Published: Dec. 24, 2018

In this review, we summarize the origin and advancements of iridium-catalyzed asymmetric allylic substitution reactions during past two decades. Since first report in 1997, Ir-catalyzed have attracted intense attention due to their exceptionally high regio- enantioselectivities. been significantly developed recent years many respects, including ligand development, mechanistic understanding, substrate scope, application synthesis complex functional molecules. an explicit outline ligands, mechanism, scope nucleophiles, applications is presented.

Language: Английский

---

Synergistic Dual Transition Metal Catalysis

Chemical Reviews, Journal Year: 2020, Volume and Issue: 120(24), P. 13382 - 13433

Published: Nov. 29, 2020

Synergistic catalysis, a type of plural catalysis which utilizes at least two different catalysts to enable reaction between separately activated substrates, has unlocked plethora previously unattainable transformations and novel chemical reactivity. Despite the appreciable utility synergistic specific examples involving transition metals have been limited, as ensuring judicious choice parameters prevent deactivation catalysts, undesirable monocatalytic event(s) leading side products, or premature termination other potentially troublesome outcomes present formidable challenge. Excluding those driven by photocatalytic mechanisms, this review will highlight reported reactions that make use simultaneous catalytic cycles metal catalysts.

Language: Английский

---

Stereodivergent Coupling of 1,3-Dienes with Aldimine Esters Enabled by Synergistic Pd and Cu Catalysis

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(37), P. 14554 - 14559

Published: Sept. 3, 2019

Herein we describe the use of synergistic Pd and Cu catalysis for stereodivergent coupling reactions between 1,3-dienes aldimine esters. By using different enantiomers two metal catalysts, all four stereoisomers products, which have vicinal stereocenters, could be accessed with high diastereo- enantioselectivity. This atom-economical cross-coupling reaction has a wide substrate scope good functional group tolerance. Our work highlights power asymmetric involving Pd-hydride catalysts.

Language: Английский

---

Catalytic Asymmetric Reactions with N-Metallated Azomethine Ylides

Accounts of Chemical Research, Journal Year: 2020, Volume and Issue: 53(5), P. 1084 - 1100

Published: April 22, 2020

ConspectusOptically active nitrogen-containing compounds have attracted substantial attention due to their ubiquity in the cores of natural products and bioactive molecules. Among various synthetic approaches nitrogenous frameworks, catalytic asymmetric 1,3-dipolar cycloadditions are one most attractive methods because powerful ability rapidly construct chiral N-heterocycles. In particular, N-metallated azomethine ylides, common readily available 1,3-dipoles, been extensively applied dipolar cycloaddition reactions. Despite fact that transformations ylides investigated for decades, efforts directed toward preparation pyrrolidines using glycinate-derived α-unsubstituted aldimine esters as precursors ylides. While α-substituted derived from amino other than glycinate seldom harnessed, construction non-five-membered N-heterocycles via remains underexplored. addition, α-functionalization prepare acyclic such α-amino acids, which an situ-generated ylide serves nucleophile, has not sufficiently described.In this Account, we mainly discuss achievements made past decade broadening applications compounds. We began our investigation with design synthesis a new type ligand, TF-BiphamPhos, only coordinates Lewis acids activate species but also H-bond donor increase reactivity dipolarophiles significantly enhanced stereochemical control. Using Cu(I) or Ag(I)/TF-BiphamPhos complex catalyst, achieved highly stereoselective (3+2) non-glycinate-derived diverse dipolarophiles, producing variety enantioenriched multiple stereocenters single step. To further expand utility successfully developed higher order fulvenes, tropone, 2-acyl cycloheptatrienes, pyrazolidinium serving reaction partner, provides straightforward access fused piperidines, bridged azabicyclic triazines (3+6)- (3+3)-type cycloadditions. realized Cu(I)-catalyzed 1,4-Michael additions α,β-unsaturated bisphosphates/Morita–Baylis–Hillman products, furnishing array structurally unnatural acids. Based on strategy synergistic activation, efficient dual Cu/Pd Cu/Ir catalysis allylic/allenylic alkylation Notably, allowed stereodivergent α,α-disubstituted branched allylic reaction, two distinct metal catalysts independently full control over corresponding nucleophile electrophile. Furthermore, expedient biologically important tetrahydro-γ-carbolines was through Cu/Ir-catalyzed cascade allylation/iso-Pictet–Spengler cyclization. when steric congestion allylation intermediates increased, combined provided allylation/2-aza-Cope rearrangement, optically homoallylic amines impressive results.

Language: Английский

---

2-Azaallyl Anions, 2-Azaallyl Cations, 2-Azaallyl Radicals, and Azomethine Ylides

Chemical Reviews, Journal Year: 2018, Volume and Issue: 118(20), P. 10393 - 10457

Published: Oct. 10, 2018

This review covers the use of 2-azaallyl anions, cations, and radicals in organic synthesis up through June 2018. Particular attention is paid to both foundational studies recent advances over past decade involving semistabilized nonstabilized anions as key intermediates various carbon–carbon carbon–heteroatom bond-forming processes. Both transition-metal-catalyzed transition-metal-free transformations are covered. Azomethine ylides, which have received significant elsewhere, discussed briefly with primary focus on critical comparisons regard generation use.

Language: Английский

---

Challenges and Opportunities in Multicatalysis

ACS Catalysis, Journal Year: 2021, Volume and Issue: 11(7), P. 3891 - 3915

Published: March 15, 2021

Multicatalysis is an emerging field targeting the development of efficient catalytic transformations to quickly convert relatively simple starting materials into more complex value-added products. Within multicatalytic processes either multiple catalysts execute single reactions or precise sequences occur in a "one-pot" fashion. Attractively, protocols not only enable that are inaccessible through classic approaches but also able significantly reduce time, waste, and cost synthetic processes, making organic synthesis resources efficient. In this Perspective article, we review different strategies multicatalysis bring distinct challenges opportunities. We divide overarching three main categories: cooperative, domino, relay catalysis. Each category described along with representative examples highlight its features. Special emphasis dedicated catalysis, which further discussed subcategories. Lastly, provide analysis systems incorporate higher levels complexity underscore potential systems.

Language: Английский

---

Stereodivergent Construction of Tertiary Fluorides in Vicinal Stereogenic Pairs by Allylic Substitution with Iridium and Copper Catalysts

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(33), P. 13066 - 13073

Published: July 25, 2019

Although much effort has been spent on the enantioselective synthesis of tertiary alkyl fluorides, compounds containing such a stereogenic center within an array stereocenters, particularly two vicinal ones, remains synthetic challenge, and no method to control configuration each independently reported. We describe strategy achieve stereodivergent centers, one fluorine atom, by forming connecting carbon-carbon bond with catalyst system comprising iridium complex that controls at electrophilic carbon copper nucleophilic fluorine-containing carbon. These reactions occur alkyl- aryl-substituted allylic esters unstabilized enolates azaaryl ketones, esters, amides in high yield, diastereoselectivity, enantioselectivity (generally >90% >20:1 dr, 97-99% ee). Access all four stereoisomers products demonstrates precise configurations independently. This methodology extends construction quaternary stereocenters similarly yield selectivity. DFT calculations uncover origin stereoselectivity enolate substitution.

Language: Английский

---

Stereodivergent Pd/Cu Catalysis for the Dynamic Kinetic Asymmetric Transformation of Racemic Unsymmetrical 1,3-Disubstituted Allyl Acetates

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(18), P. 8097 - 8103

Published: April 19, 2020

A stereodivergent Pd/Cu catalyst system has been developed for the unprecedented dynamic kinetic asymmetric transformation (DyKAT) of racemic unsymmetrical 1,3-disubstituted allylic acetates with prochiral aldimine esters. series α,α-disubstituted α-amino acids bearing vicinal stereocenters were easily prepared excellent enantioselectivities (up to >99% ee) and diastereoselectivities >20:1 dr). Moreover, all four stereoisomers product can be readily obtained simply by switching configurations two chiral metal catalysts. Furthermore, present work highlights power synergistic catalysis consisting common bidentate ligands synthesis.

Language: Английский

---

Stereodivergent Synthesis of Tertiary Fluoride-Tethered Allenes via Copper and Palladium Dual Catalysis

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(19), P. 7285 - 7291

Published: May 10, 2021

Herein we describe a protocol for the unprecedented stereodivergent synthesis of tertiary fluoride-tethered allenes bearing stereogenic center and axis via Cu/Pd synergistic catalysis. A broad scope conjugated enynes are coupled with various α-fluoroesters in high yields diastereoselectivities generally >99% ee. In addition, four stereoisomers allene products ensure precise access to corresponding fluorinated hydrofurans novel axial-to-central chirality transfer process.

Language: Английский

---

Enantio- and Diastereodivergent Construction of 1,3-Nonadjacent Stereocenters Bearing Axial and Central Chirality through Synergistic Pd/Cu Catalysis

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(32), P. 12622 - 12632

Published: Aug. 5, 2021

In contrast to the widely explored methods for asymmetric synthesis of molecules bearing a single stereocenter or adjacent stereocenters, concurrent construction 1,3-stereogenic centers in an enantio- and diastereoselective manner remains challenge, especially acyclic systems. Herein, we report diastereodivergent 1,3-nonadjacent stereocenters allenyl axial central chirality through synergistic Pd/Cu-catalyzed dynamic kinetic allenylation with racemic allenylic esters. The protocol is suitable wide range substrates including challenging esters less sterically bulky substituents provided chiral products high levels diastereoselectivities (up >20:1 dr >99% ee). Furthermore, several representative transformations involving axial-to-central transfer were conducted, affording useful structural motifs containing nonadjacent manner.

Language: Английский

---