Nickel‐Catalyzed Barton Decarboxylation and Giese Reactions: A Practical Take on Classic Transforms

Qin, Tian; Malins, Lara R.; Edwards, Jacob T.; Merchant, Rohan R.; Novák, A.; Zhong, Jacob Z.; Mills, Riley B.; Yan, Ming; Yuan, Changxia; Eastgate, Martin D.; Baran, Phil S.

doi:10.1002/ange.201609662

Cited by 89 publications

(49 citation statements)

References 55 publications

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“…On the basis of the above results and literature precedent, [6][7][8][9] we propose the reaction mechanism in Scheme 3. [a] Reaction conditions: redox-active ester (0.2 mmol), R 2 Zn (0.66 mmol), CoBr 2 (20 mol %), in DMF (0.4 m), room temperature, 15 h; yields are for the isolated product.…”

Section: Angewandte Chemiementioning

confidence: 83%

“…The method enabled efficient alkylaryl, alkyl-alkenyl, and alkyl-alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. [5] Advances by the Baran research group showed that low-valent first-row transition metals,i ncluding nickel [6] and iron, [6h,g, 7] were also effective in abroad range of decarboxylative cross-coupling reactions without the need for light irradiation. Mechanistic studies indicated that aradical mechanism is involved.…”

mentioning

confidence: 99%

“…[1] While organohalides have enjoyed as uccess as the electrophilic coupling partners,r ecent years have witnessed ag rowing interest in the use of aliphatic carboxylic acids (or their derivatives) as alkyl halide surrogates in such reactions. [5] Advances by the Baran research group showed that low-valent first-row transition metals,i ncluding nickel [6] and iron, [6h,g, 7] were also effective in abroad range of decarboxylative cross-coupling reactions without the need for light irradiation. [5] Advances by the Baran research group showed that low-valent first-row transition metals,i ncluding nickel [6] and iron, [6h,g, 7] were also effective in abroad range of decarboxylative cross-coupling reactions without the need for light irradiation.…”

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confidence: 99%

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Decarboxylative Negishi Coupling of Redox‐Active Aliphatic Esters by Cobalt Catalysis

et al. 2018

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Ac obalt-catalyzed decarboxylative Negishi coupling reaction of redox-active aliphatic esters with organozinc reagents was developed. The method enabled efficient alkylaryl, alkyl-alkenyl, and alkyl-alkynyl coupling reactions under mild reaction conditions with no external ligand or additive needed. The success of an in situ activation protocol and the facile synthesis of the drug molecule (AE)-preclamol highlight the synthetic potential of this method. Mechanistic studies indicated that aradical mechanism is involved.Transition-metal-catalyzed cross-coupling reactions to forge C À Cb onds are of vital importance in modern organic synthesis. [1] While organohalides have enjoyed as uccess as the electrophilic coupling partners,r ecent years have witnessed ag rowing interest in the use of aliphatic carboxylic acids (or their derivatives) as alkyl halide surrogates in such reactions. [2] Advantages are apparent not only in the wide availability of carboxylic acids,b ut also in that alkyl halides are typically unstable,c hallenging to prepare,a nd undergo oxidative addition to transition metals with difficulty.B y activating the carboxylic acid to the corresponding redoxactive ester,s ingle-electron-transfer reduction is feasible to generate an alkyl radical through the extrusion of CO 2 .T his radical-generation process has been involved in diverse carbon-carbon and carbon-heteroatom bond forming reactions based on single photocatalytic systems [3] or dual catalytic systems [4] combining photoredox catalysis with transitionmetal catalysis. [5] Advances by the Baran research group showed that low-valent first-row transition metals,i ncluding nickel [6] and iron, [6h,g, 7] were also effective in abroad range of decarboxylative cross-coupling reactions without the need for light irradiation. Very recently,acopper-catalyzed decarboxylative radical silylation of redox-active aliphatic esters was also developed. [8] Inspired by these elegant studies,w e reasoned that al ow-valent cobalt catalyst could also donate an electron to the redox-active ester, [9] thereby triggering alkyl radical formation and af ollow-up cross-coupling reaction.Cobalt, as an earth-abundant and low-toxic first-row transition metal, has been previously identified as an attrac-tive catalyst enabling the effective coupling of aryl, [10] alkenyl, [11] and alkynyl halides [12] (or their pseudohalides) with organozinc compounds (Figure 1a). Nevertheless,t he use of unactivated alkyl electrophiles [13] in cobalt-catalyzed Negishi coupling reactions is only recent. [14] In 2015, Knochel and co-workers reported an elegant cobalt-catalyzed crosscoupling reaction of (hetero)aryl zinc reagents with primary and secondary alkyl iodides;a lkyl bromides were also applicable but with lower efficiency. [14a] We report herein ac obalt-catalyzed decarboxylative Negishi coupling of activated aliphatic carboxylic acids under mild reaction conditions ( Figure 1b). Ther eaction allowed the synthesis of ab road range of alkylated arenes,a lkenes,a nd alkynes by reaction...

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Section: Angewandte Chemiementioning

confidence: 83%

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confidence: 99%

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confidence: 99%

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Decarboxylative Negishi Coupling of Redox‐Active Aliphatic Esters by Cobalt Catalysis

et al. 2018

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“…109,110 Focusing instead on postassembly synthetic transformations, it is unsurprising that the aforementioned chemoselectivity challenges (see the discussion of Asp and Glu in Polar, Ionizable Side Chains) apply to α -carboxylic acids as well. Nevertheless, orthogonal protecting group strategies and judicious sequence choice have been employed to enable several decarboxylative functionalizations of α -acids, including 1,4-additions (entry 44), 79 heteroarylations (entry 45), 80,81 and borylations (entry 46). 82 …”

Section: C-terminus and N-terminusmentioning

confidence: 99%

Residue-Specific Peptide Modification: A Chemist’s Guide

2017

Self Cite

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Advances in bioconjugation and native protein modification are appearing at a blistering pace, making it increasingly time consuming for practitioners to identify the best chemical method for modifying a specific amino acid residue in a complex setting. The purpose of this perspective is to provide an informative, graphically rich manual highlighting significant advances in the field over the past decade. This guide will help triage candidate methods for peptide alteration and will serve as a starting point for those seeking to solve long-standing challenges.

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“…Redox‐active esters were either isolated or formed in situ and then reacted with a nickel or iron catalyst and one of the eight ligands, L1–L8, shown in Figure . The majority of the reactions described in this review used ligands L1, L2, L3, or L5 . During the reaction, redox‐active esters react with the nickel or iron catalyst to eliminate carbon dioxide through electron transfer redox chemistry to generate a radical intermediate which reacts with various compounds to generate a wide range of products as shown in Scheme .…”

Section: Redox‐active Estersmentioning

confidence: 99%

New radical methods for the potential synthesis of carbon‐13 and carbon‐14 labeled complex products

Maxwell

2018

Labelled Comp Radiopharmac

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The isotopic labeling of molecules for agrichemical and pharmaceutical uses is becoming more challenging as molecules become larger, involve more stereochemistry, and as intellectual property rights become more complex. As such, isotope chemists need to continually add new isotopic methods to their armamentarium to successfully label complex molecules with carbon-13 and carbon-14. Recently, there has been a surge in the use of radicals to form new carbon-carbon bonds and for the incorporation of functional groups which can be used to incorporate isotopically labeled carbons. This review will describe some potential new radical methods for incorporating isotopically labeled carbon into complex molecules or into substrates that can be attached to late stage intermediates to generate labeled products.

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Nickel‐Catalyzed Barton Decarboxylation and Giese Reactions: A Practical Take on Classic Transforms

Cited by 89 publications

References 55 publications

Decarboxylative Negishi Coupling of Redox‐Active Aliphatic Esters by Cobalt Catalysis

Decarboxylative Negishi Coupling of Redox‐Active Aliphatic Esters by Cobalt Catalysis

Residue-Specific Peptide Modification: A Chemist’s Guide

New radical methods for the potential synthesis of carbon‐13 and carbon‐14 labeled complex products

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