Iron- and Cobalt-Catalyzed Asymmetric Hydrofunctionalization of Alkenes and Alkynes

Accounts of Chemical Research, Год журнала: 2021, Номер 54(11), С. 2701 - 2716

Опубликована: Май 20, 2021

ConspectusTransition metal catalyzed asymmetric hydrofunctionalization of readily available unsaturated hydrocarbons presents one the most straightforward and atom-economic protocols to access valuable optically active products. For decades, noble transition catalysts have laid cornerstone in this field, on account their superior reactivity selectivity. In recent years, from an economical sustainable standpoint, first-row, earth-abundant metals received considerable attention, due high natural reserves, affordable costs, low toxicity. Meanwhile, reactions also gained much interest been investigated gradually. However, since chiral ligand libraries for transition-metal catalysis are limited date, development highly enantioselective versions remains a significant challenge.This Account summarizes our efforts developing suitable ligands iron cobalt applications (hydroboration hydrosilylation) alkenes alkynes. design, we envisioned that unsymmetric NNN-tridentate (UNT) scaffolds could promote these transformations with metals. Therefore, several types UNT were designed prepared laboratory, utilizing amino acids as sources. very beginning, oxazoline iminopyridine (OIP) proposed through rational combination nitrogen-containing scaffolds. After systematic survey effects, imine moiety rigid OIP was replaced by conformationally more flexible amine unit, leading construction reactive aminoisopropylpyridine (OAP) ligands. Subsequently, imidazoline (IIP) thiazoline (TIP) altering oxygen atom nitrogen sulfur linkers, respectively. To further expand library, other tridentate containing twisted pincer, anionic, nonrigid backbone synthesized, including iminophenyl oxazolinyl phenylamine (IPOPA) phenyl picolinamide (ImPPA). The efficacy induction has demonstrated sequential alkynes, which exhibit excellent well chemo-, regio-, stereoselectivity broad functional group tolerance. Notably, regio- challenging substrates, such 1,1-disubstituted aryl terminal aliphatic alkenes, achieved. Furthermore, isomerization/hydroboration internal alkynes demonstrates synthetic power catalytic systems. enantioenriched products obtained methodologies be potentially utilized organic synthesis, medicinal chemistry, materials science. We believe continuous field would beneficial catalysis.

Язык: Английский

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Recent advances in asymmetric borylation by transition metal catalysis

Chemical Society Reviews, Год журнала: 2021, Номер 50(23), С. 13129 - 13188

Опубликована: Янв. 1, 2021

We provide a comprehensive overview of transition metal-catalysed asymmetric borylation processes to construct C–B, C–C, and other C–heteroatom bonds with considerable attention devoted the reaction modes mechanisms involved.

Язык: Английский

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Direct Synthesis of Multi(boronate) Esters from Alkenes and Alkynes via Hydroboration and Boration Reactions

ACS Catalysis, Год журнала: 2020, Номер 11(1), С. 1 - 18

Опубликована: Дек. 10, 2020

Multi(boronate) esters have been attracting increasing attention as versatile building blocks for the succinct and precise synthesis of complex molecules. However, there are a limited number efficient synthetic procedures available. In this respect, direct multiboration alkenes alkynes is undoubtedly an ideal route their synthesis. During past 30 years, catalytic systems based on transition-metals, organophosphines, bases, even catalyst-free systems, with heat or light irradiation straightforward preparation from developed. different numbers (up to 4) positional relationships adjacent boron moieties were obtained, which summarized discussed herein.

Язык: Английский

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Application of Trimethylgermanyl-Substituted Bisphosphine Ligands with Enhanced Dispersion Interactions to Copper-Catalyzed Hydroboration of Disubstituted Alkenes

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(42), С. 18213 - 18222

Опубликована: Сен. 23, 2020

We report the incorporation of large substituents based on heavy main-group elements that are atypical in ligand architectures to enhance dispersion interactions and, thereby, enantioselectivity. Specifically, we prepared chiral biaryl bisphosphine (TMG-SYNPHOS) containing 3,5-bis(trimethylgermanyl)phenyl groups phosphorus and applied this challenging problem enantioselective hydrofunctionalization reactions 1,1-disubtituted alkenes. Indeed, TMG-SYNPHOS forms a copper complex catalyzes hydroboration alkenes with high levels enantioselectivity, even when two both primary alkyl groups. In addition, catalysts bearing ligands possessing germanyl were much more active for than one derived from DTBM-SEGPHOS, 3,5-di-tert-butyl widely used copper-catalyzed hydrofunctionalization. This observation led identification DTMGM-SEGPHOS, 3,5-bis(trimethylgermanyl)-4-methoxyphenyl as phosphorus, new highly catalyst unactivated 1,2-disubstituted alkenes, class substrates has not readily undergone previously. Computational studies revealed enantioselectivity catalytic efficiency germanyl-substituted is higher silyl tert-butyl-substituted analogues because attractive between bulky trimethylgermanyl ancillary alkene substrate Pauli repulsive tended decrease

Язык: Английский

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An Olefinic 1,2‐Boryl‐Migration Enabled by Radical Addition: Construction ofgem‐Bis(boryl)alkanes

Angewandte Chemie International Edition, Год журнала: 2019, Номер 58(28), С. 9448 - 9452

Опубликована: Май 6, 2019

A series of in situ formed alkenyl diboronate complexes from Grignard reagents (commercially available or prepared bromides and Mg) with B2 Pin2 (bis(pinacolato)diboron) react diverse alkyl halides by a Ru photocatalyst to give various gem-bis(boryl)alkanes. Alkyl radicals add efficiently the complexes, adduct radical anions undergo radical-polar crossover, specifically, 1,2-boryl-anion shift boron α-carbon sp2 center. This transformation shows good functional-group compatibility can serve as powerful synthetic tool for late-stage functionalization complex compounds. Measurements quantum yield reveal that radical-chain mechanism is operative which diboronates acts reductive quencher excited state photocatalyst.

Язык: Английский

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Versatile cobalt-catalyzed regioselective chain-walking double hydroboration of 1,n-dienes to access gem-bis(boryl)alkanes

Nature Communications, Год журнала: 2020, Номер 11(1)

Опубликована: Фев. 7, 2020

Abstract Double hydroboration of dienes is the addition a hydrogen and boryl group to two double bonds diene molecule represents straightforward effective protocol prepare synthetically versatile bis(boryl)alkanes, provided that this reaction occurs selectively. However, can potentially yield several isomeric organoboron products, it still remains challenge control regioselectivity reaction, which allows selective production single product, in particular, for broad scope dienes. By employing readily available cobalt catalyst, here we show yields useful gem -bis(boryl)alkanes with excellent regioselectivity. In addition, encompasses wide range conjugated non-conjugated Furthermore, mechanistic studies indicate cobalt-catalyzed through boryl-directed chain-walking alkenylboronates generated from anti -Markovnikov 1,2-hydroboration 1,n-diene.

Язык: Английский

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A Boron Activating Effect Enables Cobalt-Catalyzed Asymmetric Hydrogenation of Sterically Hindered Alkenes

Journal of the American Chemical Society, Год журнала: 2020, Номер 142(8), С. 3923 - 3930

Опубликована: Фев. 2, 2020

Unsymmetric 1,1-diboryl alkenes bearing one -[BPin] (BPin = pinacolatoboryl) and -[BDan] (BDan 1,8-diaminonaphthalatoboryl) substituent each were hydrogenated in high yield enantioselectivity using C1-symmetric pyridine(diimine) (PDI) cobalt complexes. High activities stereoselectivities observed with an array of 2-alkyl-, 2-aryl-, 2-boryl-substituted alkenes, giving rise to enantioenriched diborylalkane building blocks. Systematic study substrate effects identified competing steric electronic demands the key activating role boron substituents, whereby sterically unencumbered boronates such as -[BDan], -[BCat] (BCat catecholatoboryl), -[Beg] (Beg ethylene glycolatoboryl) promote hydrogenation trisubstituted by enabling irreversible α-boron-directed insertion pathways achieve otherwise challenging hydrogenations alkenes. Deuterium-labeling studies support pathway generating a chiral intermediate two different substituents bound same carbon.

Язык: Английский

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Enantioselective Cobalt-Catalyzed Cascade Hydrosilylation and Hydroboration of Alkynes to Access Enantioenriched 1,1-Silylboryl Alkanes

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(33), С. 13124 - 13134

Опубликована: Авг. 12, 2021

Enantioenriched 1,1-silylboryl alkanes possess silyl and boryl groups that are both connected to the same stereogenic carbon center at well-defined orientations. As these chiral multifunctionalized compounds potentially offer two synthetic handles, they highly valued building blocks in asymmetric synthesis as well medicinal chemistry. Despite potential usefulness, efficient approaches for their preparation scarce. Seeking address this deficiency, an enantioselective cobalt-catalyzed hydrosilylation/hydroboration cascade of terminal alkynes has been realized. This protocol constitutes impressive case chemo-, regio-, stereoselectivity wherein different hydrofunctionalization events exquisitely controlled by a single set metal catalyst ligand, operation which would usually require separate catalytic systems. Downstream transformations enantioenriched 1,1-silyboryl led various valuable compounds. Mechanistic studies suggest present reaction undergoes regioselective stereocontrolled sequential hydrosilylation hydroboration processes.

Язык: Английский

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α-Boryl Organometallic Reagents in Catalytic Asymmetric Synthesis

ACS Catalysis, Год журнала: 2021, Номер 11(16), С. 10660 - 10680

Опубликована: Авг. 12, 2021

Recent years have witnessed an increase in the popularity of α-boryl organometallic reagents as versatile nucleophiles asymmetric synthesis. These compounds been adopted chemo- and stereoselective coupling reactions with a number different electrophiles. The resulting enantioenriched boronic esters can be applied stereospecific carbon-carbon or carbon-heteroatom bond construction reactions, enabling two-step strategy for complex structures high efficiency functional group compatibility. Due to these reasons, tremendous effort has devoted preparation enantiomerically enriched development related racemic prochiral materials. In this review, we describe enantio- diastereoselective that involve starting materials products showcase their synthetic utility.

Язык: Английский

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Enantioselective Cobalt-Catalyzed Hydroboration of Fluoroalkyl-Substituted Alkenes to Access Chiral Fluoroalkylboronates

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(33), С. 15333 - 15338

Опубликована: Авг. 11, 2022

Selective defluoroborylation and asymmetric hydroboration reactions of fluoroalkyl-substituted terminal alkenes with pinacolborane (HBpin) have been developed cobalt catalysts generated from Co(acac)2 bisphosphine ligands. A variety undergo this enantioselective hydroboration, affording the corresponding chiral alkylboronates containing stereogenic carbon centers high enantioselectivity (up to 98% ee). This provides a versatile foundation for synthesis organofluorine compounds centers.

Язык: Английский

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