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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Mechanism and Origins of Enantioselectivity of Cobalt-Catalyzed Intermolecular Hydroarylation/Cyclization of 1,6-Enynes with N-Pyridylindoles

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(9), P. 6438 - 6443

Published: April 11, 2022

Density functional theory calculations were performed to investigate the cobalt-catalyzed intermolecular hydroarylation/cyclization of 1,6-enynes with N-pyridylindoles. The computations reveal that reaction begins oxidative cyclization 1,6-enyne afford five-membered cobaltacycle, from which metal-assisted σ-bond metathesis/C-C reductive elimination led final product. initial constitutes rate-determining step overall reaction. steric repulsion and π···π interaction found play a crucial role in dictating experimentally observed enantioselectivity.

Language: Английский

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Copper-Catalyzed Carbonylation Reactions: A Personal Account

Synthesis, Journal Year: 2024, Volume and Issue: 56(17), P. 2595 - 2613

Published: Jan. 9, 2024

Abstract Carbonylation reactions have been widely used to construct carbonyl-containing molecules or carbon enhancement reactions, which are mostly catalyzed by noble metals (Pd, Rh, Ru, Ir). In this review, we introduce the copper-catalyzed carbonylation that developed in our group. Diverse using various substrates, including of C–H activated alkanes, difunctionalization unsaturated C–C bonds, and alkyl halides via radical pathway. 1 Introduction 2 Cu-Catalyzed C(sp 3)–H Bonds 3 Carbonylative Difunctionalization Unsaturated 4 Cu–X (H B) Mediated Acylation with Electrophiles 5 6 Alkyl Halides 7 Other Types Copper-Catalyzed Reactions 8 Conclusion Outlook

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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