Photoassisted Cobalt-Catalyzed Asymmetric Reductive Grignard-Type Addition of Aryl Iodides

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(18), P. 8347 - 8354

Published: April 28, 2022

Grignard addition is one of the most important methods used for syntheses alcohol compounds and has been known over a hundred years. However, research on asymmetric catalysis relies use organometallic nucleophiles. Here, we report first visible-light-induced cobalt-catalyzed reductive Grignard-type synthesizing chiral benzyl alcohols (>50 examples, up to 99% yield, ee). This methodology advantages mild reaction conditions, good functionality tolerance, excellent enantiocontrol, avoidance mass metal wastes, precious catalysts. Kinetic realization studies suggested that migratory insertion an aryl cobalt species into aldehyde was rate-determining step reaction.

Language: Английский

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Photoinduced Cobalt-Catalyzed Desymmetrization of Dialdehydes to Access Axial Chirality

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(12), P. 6944 - 6952

Published: March 15, 2023

Enantioselective metallaphotoredox catalysis, which combines photoredox catalysis and asymmetric transition-metal has become an effective approach to achieve stereoconvergence under mild conditions. Although many impressive synthetic approaches have been developed access central chirality, the construction of axial chirality by still remains underexplored. Herein, we report two visible light-induced cobalt-catalyzed reductive couplings biaryl dialdehydes synthesize axially chiral aldehydes (60 examples, up 98% yield, >19:1 dr, >99% ee). This protocol shows good functional group tolerance, broad substrate scope, excellent diastereo- enantioselectivity.

Language: Английский

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Catalytic Asymmetric Hydroalkoxylation and Formal Hydration and Hydroaminoxylation of Conjugated Dienes

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(7), P. 3915 - 3925

Published: Feb. 10, 2023

The straightforward construction of stereogenic centers bearing unprotected functional groups, as in nature, has been a persistent pursuit synthetic chemistry. Abundant applications free enantioenriched allyl alcohol and hydroxylamine motifs have made the asymmetric hydration hydroaminoxylation conjugated dienes from water hydroxylamine, respectively, intriguing efficient routes that have, however, unachievable thus far. A fundamental challenge is failure to realize transition-metal-catalyzed enantioselective C–O bond constructions via hydrofunctionalization dienes. Here, we perform comprehensive study toward stereoselective formal by synthesizing set new P,N-ligands identifying an aryl-derived oxime surrogate for both hydroxylamine. Asymmetric hydroalkoxylation with also elucidated. Furthermore, versatile derivatizations following provide indirect but concise hydrophenoxylation, hydrofluoroalkoxylation, hydrocarboxylation unreported Finally, ligand-to-ligand hydrogen transfer process proposed based on results preliminary mechanistic experiments.

Language: Английский

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Dienes as Versatile Substrates for Transition Metal‐Catalyzed Reactions

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(20)

Published: March 4, 2024

Abstract Dienes have been of great interest to synthetic chemists as valuable substrates due their abundance and ease synthesis. Their unique stereoelectronic properties enable broad reactivity with a wide range transition metals construct molecular complexity facilitating synthesis biologically active compounds. In addition, structural diene variation can result in substrate‐controlled reactions, providing mechanistic insights into selectivity patterns. The last decade has seen wealth new methodologies involving through the power metal catalysis. This review summarizes recent advances remaining opportunities for metal‐catalyzed transformations dienes.

Language: Английский

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A New Paradigm in Enantioselective Cobalt Catalysis: Cationic Cobalt(I) Catalysts for Heterodimerization, Cycloaddition, and Hydrofunctionalization Reactions of Olefins

Accounts of Chemical Research, Journal Year: 2021, Volume and Issue: 54(24), P. 4545 - 4564

Published: Nov. 30, 2021

One of the major challenges facing organic synthesis in 21st century is utilization abundantly available feedstock chemicals for fine chemical synthesis. Regio- and enantioselective union easily accessible 1,3-dienes other feedstocks like ethylene, alkyl acrylates, aldehydes can provide valuable building blocks adorned with latent functionalities further synthetic elaboration. Through an approach that relies on mechanistic insights systematic examination ligand counterion effects, we developed efficient cobalt-based catalytic system [(P∼P)CoX2/Me3Al] (P∼P = bisphosphine) to effect first heterodimerization several types ethylene. In addition simple cyclic acyclic dienes, siloxy-1,3-dienes participate this reaction, giving highly functionalized, nearly enantiopure silyl enolates, which be used subsequent C-C C-X bond-forming reactions. As our understanding mechanism reaction improved, attention was drawn more challenging partners acrylates (one largest volume feedstocks) as olefin instead Prompted by intrinsic limitations using aluminum alkyls activators explored fundamental chemistry lesser known (P∼P)Co(I)X species discovered presence halide sequestering agents, such sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBARF) or (C6F5)3B, certain chiral bisphosphine complexes are superb catalysts regio- acrylates. We have since found these cationic Co(I) catalysts, most conveniently prepared situ reduction corresponding cobalt(II) zinc NaBARF, promote [2 + 2]-cycloaddition between alkynes astonishing variety alkenyl derivatives give functionalized cyclobutenes. reactions 1,3-enynes alkyne ethylene followed a 1,4-addition tandem fashion cyclobutanes all-carbon quaternary center, set molecules maps well into many medicinally relevant compounds. another application, find Co(I)-catalysts selective hydroacylation 1,2-hydroboration prochiral 1,3-dienes. Further, Co(I)-catalyst promotes cycloisomerization hydroalkenylation 1,6-enynes produce carbo- heterocyclic Surprisingly regioselectivity alkene depends whether it acrylate, acrylate produces uncommon Z-adduct. This Account will summary enabling basic discoveries attendant developments led unique Co(I)-complexes disparate C-B It hope stimulate work versatile derived from earth-abundant metal.

Language: Английский

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Expedient Synthesis of Axially and Centrally Chiral Diaryl Ethers via Cobalt-Catalyzed Photoreductive Desymmetrization

ACS Catalysis, Journal Year: 2024, Volume and Issue: 14(7), P. 4638 - 4647

Published: March 12, 2024

Axially chiral diaryl ethers make up a unique class of atropisomers bearing restricted rotation about the C–O bond. Methods for expedient synthesis axially ether-based structures have been largely underdeveloped. Herein, we developed an efficient metal-catalyzed desymmetrization strategy to unveil formation and centrally dual in high diastereo- enantioselectivity. The protocol leverages cobalt-catalyzed photoreductive enantioselective couplings dialdehyde alkyne deliver stereogenicity, ether scaffold is equipped with useful synthetic handles including formyl, hydroxyl, allyl groups, as has demonstrated carboxylic acid potential ligand asymmetric catalysis.

Language: Английский

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Dual Cobalt/Organophotoredox Catalysis for Diastereo- and Regioselective 1,2-Difunctionalization of 1,3-Diene Surrogates Creating Quaternary Carbon Centers

ACS Catalysis, Journal Year: 2022, Volume and Issue: 12(6), P. 3651 - 3659

Published: March 7, 2022

The synthesis of compounds having quaternary carbon centers through a catalytic stereo- and regioselective difunctionalization 2-substituted 1,3-dienes remains elusive. Here, we present dual Co/photoredox-catalyzed cascade approach that addresses this challenge using modular vinyl cyclic carbonates functioning as masked 2-aryl-1,3-diene surrogates. latter species are conveniently prepared in situ converted into nucleophilic Co(allyl) intermediates intercepted by aldehydes to afford homoallylic alcohols with ample scope reaction partners. developed protocol marks significant step forward the use structurally versatile their 1,2-hydroalkylation 1,2-dicarbofunctionalization.

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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Ligand‐Dictated Regiodivergent Allylic Functionalizations via Palladium‐Catalyzed Remote Substitution

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(28)

Published: March 15, 2023

Different from classical allylic substitutions that require a vicinal leaving group, an olefin bearing remote group is scarcely viewed as potential allylation substrate. Herein, we describe feasible protocols to achieve regiodivergent C-H functionalizations via palladium-catalyzed substitution, which provides novel strategy for the seldomly studied migratory Tsuji-Trost reaction. Dictated by suitable ligand, process involved 4,3-hydrofunctionalization of generated conjugated diene intermediate metal walking observed in generally >20 : 1 regioselectivity. Unexpectedly, related 1,4-hydrofunctionalization pathway found be major route with newly synthesized electron-rich bisphosphine challenges conventional viewpoint on regioselectivity hydrofunctionalizations linear internal dienes η3 -substitution. A series deuterium experiments and kinetic studies provide preliminary insight into catalytic cycle.

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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