Asymmetric Transition-Metal Catalysis in the Formation and Functionalization of Metal Enolates

Vargová, Denisa; Némethová, Ivana; Plevová, Kristína; Šebesta, Radovan

doi:10.1021/acscatal.8b04357

Cited by 58 publications

(31 citation statements)

References 247 publications

(365 reference statements)

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“…These results agreed with literature reports, in which the use of Mg-and especially Zn-enolates derived from enantioselective 1,4-addition was prioritized over other metal enolates. 65…”

Section: Short Review Synthesismentioning

confidence: 99%

Are Organozirconium Reagents Applicable in Current Organic Synthesis?

Némethová

Šebesta

2020

Synthesis

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The search for mild, user-friendly, easily accessible, and robust organometallic reagents is an important feature of organometallic chemistry. Ideally, new methodologies employing organometallics should be developed with respect to practical applications in syntheses of target compounds. In this short review, we investigate if organozirconium reagents can fulfill these criteria. Organozirconium compounds are typically generated via in situ hydrozirconation of alkenes or alkynes with the Schwartz reagent. Alkyl and alkenylzirconium reagents have proven to be convenient in conjugate additions, allylic substitutions, cross-coupling reactions, and additions to carbonyls or imines. Furthermore, the Schwartz reagent itself is a useful reducing agent for polar functional groups.1 Introduction2 Synthesis and Generation of the Schwartz Reagent3 Structure and Properties of Cp2Zr(H)Cl4 Reactivity of Organozirconium Reagents4.1 Asymmetric Conjugate Addition4.2 Asymmetric Allylic Alkylations4.3 Desymmetrization Reactions4.4 Cross-Coupling Reactions4.5 1,2-Additions5 Conclusions

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“…These results agreed with literature reports, in which the use of Mg-and especially Zn-enolates derived from enantioselective 1,4-addition was prioritized over other metal enolates. 65…”

Section: Short Review Synthesismentioning

confidence: 99%

Are Organozirconium Reagents Applicable in Current Organic Synthesis?

Némethová

Šebesta

2020

Synthesis

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“…Due to its versatile reactivity, diverse bond formation, and efficiency in chemo-and stereo-selection, organometallic catalysis has always been the preeminent tools to produce chiral molecules. [5][6][7][8][9] In the last two decades, organocatalysis has emerged as another major tool for enantioselective synthesis. 10,11 Ever since, domino organocatalysis has been recognized as one of the most efficient strategies to create molecules with multiple stereocenters.…”

Section: Introductionmentioning

confidence: 99%

A hidden catalysis: metal-, and organocatalyst-free one-pot assembly of chiral aza-tricyclic molecules

2021

Preprint

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Development of a rapid synthesis of complex molecules from simple building blocks under a metal-and organocatalyst-free condition is both conceptually and chemically challenging. Here, we developed a hidden catalysis that allow the straightforward assembly of enantiopure aza-tricyclic molecules containing six contiguous stereocenters from <a>aminophenols, α,β-unsaturated aldehydes </a>and α-amino acids. <a>Without using a metal or an organocatalyst, our approach relies on a temporary formation of a spiroimidazolidinone intermediate and its participation in a sequential aza-Michael/Michael reaction as both a substrate and a catalyst</a> under an iminium/enamine catalysis. The formation of the putative iminium intermediate was supported by spectroscopic data and its interruptive reduction derivative was isolated and fully characterized. Whereas a conventional catalyst is always present and does not undergo a permanent chemical change in a classic catalysis, the spiroimidazolidinone intermediate is conceptualized as a sub-catalyst as it is only temporary produced from precursors and catalyzes its own consumption. This unique substrate-catalyst (sub-catalyst) dual role of the spiroimidazolidinone induces a substantial steric discrimination in the transition state and an excellent overall diastereoselectivity (>20:1 dr). It allows the use of an amino acid precursor as the sole chirality genesis and avoids the use of transition metals or organocatalysts. An enantiomer of an aza-tricyclic imidazolidinone can be prepared from a commercially available amino acid precursor. The aqueous-based reaction is practical and scalable for multi-gram synthesis. The success of implementing this sub-catalysis concept in the synthesis will pave the way for many efficient chiral catalyst-free preparations of chiral complex molecules.

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“…The selective reduction of carbon–carbon double bonds in α,β‐unsaturated carbonyl compounds still remains challenging in hydrogenation and hydrosilylation due to several competing reactions: 1,2‐addition, 1,4‐additions, α‐ or β‐additions to the alkene, de‐oxygenation or even polymerizations. Interestingly, among the possible 1,4‐addition products, metal‐ (or silyl‐) enol ethers or ketene acetals, are versatile nucleophiles in Mukaiyama aldol, Michael reactions, allylic alkylations, asymmetric protonations and haloketone or ketol formations …”

Section: Introductionmentioning

confidence: 99%

One‐Pot Controlled Reduction of Conjugated Amides by Sequential Double Hydrosilylation Catalyzed by an Iridium(III) Metallacycle

Corre¹,

Rysak²,

Nagyházi³

et al. 2020

Eur J Org Chem

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A single and accessible cationic iridium III metallacycle effectively catalyzes the one-pot sequential double hydrosilylation of challenging α,-unsaturated secondary and tertiary amides to afford, in a controlled and straightforward way, the corresponding reduced products, namely, the related secondary and tertiary amides and amines. The catalytic hydrosilylations of the conjugated amides described herein proceeded in good yields and high chemoselectivities. The critical silyl enolate, in [a] Y.

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Asymmetric Transition-Metal Catalysis in the Formation and Functionalization of Metal Enolates

Cited by 58 publications

References 247 publications

Are Organozirconium Reagents Applicable in Current Organic Synthesis?

Are Organozirconium Reagents Applicable in Current Organic Synthesis?

A hidden catalysis: metal-, and organocatalyst-free one-pot assembly of chiral aza-tricyclic molecules

One‐Pot Controlled Reduction of Conjugated Amides by Sequential Double Hydrosilylation Catalyzed by an Iridium(III) Metallacycle

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