P-Stereogenic Phosphorus Ligands in Asymmetric Catalysis

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(14), P. 8657 - 8739

Published: July 2, 2024

Chiral phosphorus ligands play a crucial role in asymmetric catalysis for the efficient synthesis of useful optically active compounds. They are largely categorized into two classes: backbone chirality and P-stereogenic ligands. Most reported belong to former class. Privileged ones such as BINAP DuPhos frequently employed wide range catalytic transformations. In contrast, latter class has remained small family many years mainly because their synthetic difficulty. The late 1990s saw emergence novel with superior enantioinduction ability Rh-catalyzed hydrogenation reactions. Since then, numerous have been synthesized used This Review summarizes thus far, including stereochemical electronic properties that afford high excellent enantioselectivities. Examples reactions use this described together applications construction key intermediates natural products therapeutic agents. literature covered dates back 1968 up until December 2023, centering on studies published later years.

Language: Английский

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Enantioselective Reductive (Hetero)Arylation of Cyclic N‐Sulfonyl Imines by Cobalt Catalysis

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(19)

Published: March 14, 2023

Transition-metal-catalyzed enantioselective addition of aryl organometallic reagents to imines has emerged as one the most powerful tools for formation optically active diarylmethylamines. Here, we report first asymmetric reductive (hetero)arylations using and heteroaryl halides enabled by a chiral cobalt-bisphosphine catalyst. This approach shows good functional group compatibility complements reported strategy without use reagents. Mechanistic investigations supported that aryl-cobalt, instead an arylzinc reagent, was formed in situ this aryl-addition event.

Language: Английский

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Ligand Control in Co-Catalyzed Regio- and Enantioselective Hydroboration: Homoallyl Secondary Boronates via Uncommon 4,3-Hydroboration of 1,3-Dienes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7462 - 7481

Published: March 27, 2023

Enantiopure homoallylic boronate esters are versatile intermediates because the C-B bond in these compounds can be stereospecifically transformed into C-C, C-O, and C-N bonds. Regio- enantioselective synthesis of precursors from 1,3-dienes has few precedents literature. We have identified reaction conditions ligands for nearly enantiopure (er >97:3 to >99:1) via a rarely seen cobalt-catalyzed [4,3]-hydroboration 1,3-dienes. Monosubstituted or 2,4-disubstituted linear dienes undergo highly efficient regio- hydroboration with HBPin catalyzed by [(L*)Co]+[BARF]-, where L* is typically chiral bis-phosphine ligand narrow bite angle. Several such (e.g., i-PrDuPhos, QuinoxP*, Duanphos, BenzP*) that give high enantioselectivities product been identified. In addition, equally challenging problem regioselectivity uniquely solved dibenzooxaphosphole ligand, (R,R)-MeO-BIBOP. A cationic cobalt(I) complex this very (TON >960) catalyst while also providing excellent regioselectivities (rr >98:2) broad range substrates. detailed computational investigation reactions using Co complexes two widely different (BenzP* MeO-BIBOP) employing B3LYP-D3 density functional theory provides key insights mechanism origins selectivities. The results full agreement experiments. For we examined thus far, relative stabilities diastereomeric diene-bound [(L*)Co(η4-diene)]+ lead initial diastereofacial selectivity, which turn retained subsequent steps, exceptional enantioselectivity reactions.

Language: Английский

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Catalytic Asymmetric Synthesis of Zinc Metallacycles

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(37), P. 20152 - 20157

Published: Sept. 11, 2023

Transition-metal-catalyzed reductive coupling reactions of alkynes and imines are attractive methods for the synthesis chiral allylic amines. Mechanistically, these involve oxidative cyclization alkyne imine to generate a metallacyclic intermediate, which then reacts with H2 or surrogate form product. As an alternative this hydrogenolysis pathway, here we show that transmetalation zinc can occur, forming metallacycle This organozinc product serves as versatile nucleophile carbon-carbon carbon-heteroatom reactions. Mechanistic studies based on isotopic labeling experiments DFT calculations suggest key step occurs between Co(II) species ZnCl2.

Language: Английский

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Pathway-divergent coupling of 1,3-enynes with acrylates through cascade cobalt catalysis

Nature Communications, Journal Year: 2024, Volume and Issue: 15(1)

Published: April 23, 2024

Catalytic cascade transformations of simple starting materials into highly functionalized molecules bearing a stereochemically defined multisubstituted alkene, which are important in medicinal chemistry, natural product synthesis, and material science, high demand for organic synthesis. The development multiple reaction pathways accurately controlled by catalysts derived from different ligands is critical goal the field catalysis. Here we report cobalt-catalyzed strategy direct coupling inexpensive 1,3-enynes with two acrylates to construct diversity 1,3-dienes containing trisubstituted or tetrasubstituted olefin. Such reactions can proceed through three initiated oxidative cyclization achieve bond formation chemo-, regio- stereoselectivity precisely ligands, providing platform tandem carbon-carbon bond-forming reactions.

Language: Английский

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Enantioselective Cross-[4 + 2]-Cycloaddition/Decarboxylation of 2-Pyrones by Cooperative Catalysis of the Pd(0)/NHC Complex and Chiral Phosphoric Acid

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6936 - 6946

Published: Feb. 28, 2024

Here, we describe a cooperative Pd(0)/chiral phosphoric acid catalytic system that allows us to realize the first chemo-, regio-, and enantioselective sequential cross-[4 + 2]-cycloaddition/decarboxylation reaction between 2-pyrones unactivated acyclic 1,3-dienes. The key success of this transformation is utilization an achiral N-heterocyclic carbene (NHC) as ligand newly developed chiral cocatalyst. Experimental investigations computational studies support idea Pd(0)/NHC complex acts π-Lewis base increase nucleophilicity 1,3-dienes via η2 coordination, while simultaneously increases electrophilicity by hydrogen bonding. By synergistic catalysis, 2]-cycloaddition decarboxylation proceeds efficiently, enabling preparation wide range vinyl-substituted 1,3-cyclohexadienes in good yields enantioselectivities. synthetic utility demonstrated transformations product various valuable six-membered carbocycles.

Language: Английский

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Cobalt-Catalyzed Enantioselective Hydroboration of α-Substituted Acrylates

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(10), P. 6604 - 6617

Published: March 3, 2024

Even though metal-catalyzed enantioselective hydroborations of alkenes have attracted enormous attention, few preparatively useful reactions α-alkyl acrylic acid derivatives are known, and most use rhodium catalysts. No examples asymmetric hydroboration the corresponding α-arylacrylic esters known. In our continuing efforts to search for new applications earth-abundant cobalt catalysts broadly applicable organic transformations, we identified 2-(2-diarylphosphinophenyl)oxazoline ligands mild reaction conditions efficient highly regio- α-alkyl- α-aryl- acrylates, giving β-borylated propionates. Since C-B bonds in these compounds can be readily replaced by C-O, C-N, C-C bonds, intermediates could serve as valuable chiral synthons, some from feedstock carbon sources, synthesis propionate-bearing motifs including polyketides related molecules. Two-step syntheses "Roche" ester methyl methacrylate (79%; er 99:1), arguably widely used fragment polyketide synthesis, tropic (∼80% yield; ∼93:7), which potential several medicinally important classes compounds, illustrate power methods. Mechanistic studies confirm requirement a cationic Co(I) species [(

Language: Английский

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Chemodivergent, Regio‐ and Enantioselective Cycloaddition Reactions between 1,3‐Dienes and Alkynes

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 62(8)

Published: Dec. 15, 2022

Alkynes and 1,3-dienes are among the most readily available precursors for organic synthesis. We report two distinctly different, catalyst-dependent, modes of regio- enantioselective cycloaddition reactions between these classes compounds providing rapid access to highly functionalized 1,4-cyclohexadienes or cyclobutenes from same precursors. Complexes an earth abundant metal, cobalt, with several commercially chiral bisphosphine ligands narrow bite angles catalyze [4+2]-cycloadditions a 1,3-diene alkyne giving cyclohexa-1,4-diene in excellent chemo-, enantioselectivities. In sharp contrast, complex finely tuned phosphino-oxazoline ligand promotes unique [2+2]-cycloaddition terminal double bond diene cyclobutene

Language: Английский

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Ligand Effects in Carboxylic Ester- and Aldehyde-Assisted β-C–H Activation in Regiodivergent and Enantioselective Cycloisomerization–Hydroalkenylation and Cycloisomerization–Hydroarylation, and [2 + 2 + 2]-Cycloadditions of 1,6-Enynes

Journal of the American Chemical Society, Journal Year: 2024, Volume and Issue: 146(27), P. 18753 - 18770

Published: June 27, 2024

Herein, we report room temperature, atom-economic protocols for high regio- and enantioselective tandem cycloisomerization–hydroarylation cycloisomerization–hydroalkenylation of 1,6-enynes leading to vicinal carba-functionalized pyrrolidines, tetrahydrofurans, cyclopentanes. The latter steps in these processes involve carbonyl-coordination-assisted ortho-C–H activation aromatic aldehydes esters, and, a similar, yet rarely seen, β-C–H the case acrylates. Synthetically useful versions such reactions are rare limited C2–H indoles pyrroles. A similar reaction is also observed with N-vinylphthalimide, which has carbonyl group suitable C–H activation. dibenzooxaphosphole ligand, (2S,2S′,3S,3S′)-MeO-BIBOP was uniquely identified as crucial achieving challenging enantioselectivity. This methodology gives access substituted five-membered carbo- heterocyclic compounds good yields excellent enantioselectivities under low catalyst loading. primary KIE 3.5 an intermolecular competition experiment methyl benzoate d5-methyl benzoate, indicates that cleavage turnover-limiting step this process. Unlike acrylates, undergoes exclusive hydroalkenylation, β, γ-unsaturated ester, but-3-enoate, highly cycloisomerization-coupling sequence 1,6-enyne giving either [2 + 2 2]-cycloaddition (S, S)-BDPP or hydroalkenylation (2S,2′S,3S,3′S)-MeO-BIBOP depending on ligand employed. (E)-configuration newly formed double bond at terminal alkynyl carbon (of starting enyne) product β,γ-unsaturated ester suggests more classical migratory insertion-β-hydride elimination route formation product.

Language: Английский

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Recent Advances in Asymmetric Synthesis of Chiral Cyclobutenes

ChemCatChem, Journal Year: 2023, Volume and Issue: 16(3)

Published: Nov. 21, 2023

Abstract Cyclobutene scaffolds occur in natural products and bioactive compounds. Their unique structural features intrinsic ring strain make cyclobutene a type of important building block synthetic chemistry. In recent years, considerable efforts have been dedicated to the synthesis chiral cyclobutenes. Enantioselective [2+2] cycloadditions functionalization derivatives emerged as powerful reliable protocols for achieving this goal, resulting significant progress field. This review provides comprehensive summary advancements asymmetric cyclobutenes, discussion is logically divided into four parts according reaction mode.

Language: Английский

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