Applications of Chiral Three-membered Rings for Total Synthesis: A Review

Dalpozzo, Renato; Lattanzi, Alessandra; Pellissier, Hélène

doi:10.2174/1385272821666170221151356

Cited by 25 publications

(10 citation statements)

References 147 publications

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“…The ability to set stereochemistry during a catalytic reaction is a critical tool in synthetic chemistry, and three‐membered ring formation is an increasingly active research topic . The reason is that prochiral alkenes are widely abundant and can be combined with a variety of oxidants.…”

Section: Introductionmentioning

confidence: 99%

A Chiral Macrocyclic Tetra‐N‐Heterocyclic Carbene Yields an “All Carbene” Iron Alkylidene Complex

DeJesus

Jenkins

2020

Chemistry A European J

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The first chiral macrocyclic tetra-N-heterocyclic carbene (NHC) ligand has been synthesized. The macrocycle, prepared in high yield andl arge scale,w as ligatedo ntop alladium and iron to give divalent C 2 -symmetric square planar complexes. Multinuclear NMR and single crystal X-ray diffraction demonstrated that there are two distinct NHCs on each ligand,d ue to the bridging chiral cyclohexane. Oxidationo f the iron(II) complex with trimethylamine N-oxide yielded a bridgingo xo complex.D iazodiphenylmethane reactedwith the iron(II) complex at room temperature to give ap aramag-netic diazoalkane complex;t he same reaction yieldedt he "all carbene" complexa te levated temperature. Electrochemical measurements support the assignment of the "all carbene"c omplex being an alkylidene. Notably,t he diazoalkane complex can be directly transformed into the alkylidene complex, which had not been previously demonstrated on iron. Finally,atest catalytic reactionw ithad iazoalkane on the iron(II) complex does not yield the expected cyclopropane,b ut actually the azine compound.[a] Dr.

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Section: Introductionmentioning

confidence: 99%

A Chiral Macrocyclic Tetra‐N‐Heterocyclic Carbene Yields an “All Carbene” Iron Alkylidene Complex

DeJesus

Jenkins

2020

Chemistry A European J

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“…The highly strained heterocycles, oxiranes and oxetanes, have long played key roles in the synthesis of small molecules and materials. , These moieties can also be found in a variety of natural products . Arguably, because of the facility with which they are synthesized, particularly in an asymmetric fashion, − the prominence of epoxides outstrips that of their homologous counterparts.…”

Section: Introductionmentioning

confidence: 99%

Unusual Transformations of Strain-Heightened Oxetanes

Riel

Howell

2021

Acc. Chem. Res.

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Conspectus Oxetanes are important motifs for drug discovery and are valuable templates in organic synthesis. Much of their use as synthetic intermediates exploits their inherent strain, often resulting in chain extensions at the expense of the heterocycle. Modifications on the carbon alpha to the oxygen of oxetanes, such as the CO of β-lactones, extend the modes of reactivity. Nevertheless, the outcomes are still largely predictable. On the other hand, other alpha modifications, such as a CH2, a spiro-oxiranyl moiety, or a spiro-cyclopropyl group, increase strain and open pathways not available to simple oxetanes or β-lactones. Methods in generating 2-methyleneoxetanes, 1,5-dioxaspiro[3.2]hexanes, and 4-oxaspiro[2.3]hexanes have been developed by us and others. To date, reactions of these systems have sometimes been predictable, but often the outcomes have been unexpected. This has provided fertile ground for thinking about what controls reactivity and what other reaction pathways might be accessible to these strain-heightened oxetanes. This Account summarizes the published literature on the most straightforward approaches to 2-methyleneoxetanes, dioxaspirohexanes, and oxaspirohexanes and on their reactivity. In contrast to simple oxetanes, reactions of 2-methyleneoxetanes with nucleophiles at C4 release an enolate rather than an alkoxide. Also, 2-methyleneoxetanes can be converted to homopropargyl alcohols or undergo a silicon accelerated isomerization/electrocyclic ring opening, processes accessible only because of the exocyclic double bond. In addition, oxetane oxocarbenium ions, derived from protonation of the enol ether, can react with nucleophiles to provide 2,2-disubstituted oxetanes. Oxaspirohexanes are readily prepared by Simmons–Smith cyclopropanation of 2-methyleneoxetanes. These unusual systems undergo a variety of substituent dependent rearrangements in the presence of the Lewis acid BF3·Et2O. In addition, upon treatment with Zeise’s dimer, oxaspirohexanes are transformed to synthetically useful 3-methylenetetrahydrofurans. Dioxaspirohexanes are easily accessed by dimethyldioxirane oxidation of 2-methyleneoxetanes. Predictably, dioxaspirohexanes react with many nucleophiles to give α-functionalized-β′-hydroxy ketones. Unexpectedly, 2,2-disubstituted oxetanes can also be selectively produced. This latter pathway has led to further unusual transformations, illuminating computational studies, and novel routes to biologically relevant molecules.

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“…Enantioselective epoxides are the central building blocks in the synthesis of chiral organic structures. [1,2] Epoxides are extensively distributed in many biologically relevant natural products. [3] Moreover, establishment of epoxide scaffolds are significant and applicable to gain versatile structures in synthetic organic chemistry.…”

Section: Introductionmentioning

confidence: 99%

Recent advances and trends in the biomimetic iron‐catalyzed asymmetric epoxidation

Radhika

Aneeja

Philip

et al. 2021

Applied Organom Chemis

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Enantiomerically pure epoxides are extremely beneficial structural scaffolds in synthetic organic and medicinal chemistry. Complexes based on iron with ligands featuring oxygen or nitrogen atom donors gained much recognition and interest in catalysis owing to the propensity of these complexes in realizing various reactions including epoxidation. This review is devoted to the recent prospects and developments in biomimetic iron-catalyzed asymmetric epoxidation and summarizes reports during the period 2014 to 2020.

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Applications of Chiral Three-membered Rings for Total Synthesis: A Review

Cited by 25 publications

References 147 publications

A Chiral Macrocyclic Tetra‐N‐Heterocyclic Carbene Yields an “All Carbene” Iron Alkylidene Complex

A Chiral Macrocyclic Tetra‐N‐Heterocyclic Carbene Yields an “All Carbene” Iron Alkylidene Complex

Unusual Transformations of Strain-Heightened Oxetanes

Recent advances and trends in the biomimetic iron‐catalyzed asymmetric epoxidation

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