Ammonium Ylide Mediated Cyclization Reactions

Roiser, Lukas; Zielke, Katharina; Waser, Mario

doi:10.1002/ajoc.201800091

Cited by 46 publications

(41 citation statements)

References 99 publications

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“…Still, pioneering work of Gaunt et al . described ammonium ylides in diastereo‐ and enantioselective cyclopropanation reactions, and also three‐ and five‐membered heterocycles were synthesized, including aziridines and epoxides, isoxazoline N ‐oxides, pyrazoles, pyrroles, spirocyclic oxindoles and dihydrofurans…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Ammonium Ylide Mediated One‐Pot Synthesis of Highly Substituted γ‐Butyrolactones

et al. 2020

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An ammonium ylide mediated access towards trans‐β,γ‐disubstituted, all‐trans‐α,β,γ‐trisubstituted, and α,α,β,γ‐tetrasubstituted γ‐butyrolactones bearing a broad variety of functionalities was developed. Starting from widely accessible benzylidene Meldrum's acid derivatives and α‐bromo carbonyl compounds, γ‐butyrolactones were obtained in yields between 32–99% with up to excellent diastereoselectivities (>95:5) via a DABCO‐mediated [2+1] annulation. Utilization of enantiomerically pure cinchona alkaloid derivatives enables the first asymmetric ammonium ylide mediated method to provide (3R, 4R)‐β,γ‐disubstituted and (2R, 3R, 4R)‐α,β,γ‐trisubstituted γ‐butyrolactones in moderate to good yields with up to very good enantiomeric ratios (97:3). The scalability of the transformation was proven while determining the absolute configuration.

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Section: Introductionmentioning

confidence: 99%

Enantioselective Ammonium Ylide Mediated One‐Pot Synthesis of Highly Substituted γ‐Butyrolactones

et al. 2020

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“…Among mentioned synthetic routines, the last ones have a significant position. Ylides, the onium group, are used as efficient reagents in various organic syntheses . The generally presented mechanism for this reaction includes three steps: addition, bond rotation, and intramolecular cyclization (elimination).…”

Section: Introductionmentioning

confidence: 99%

“…In the second step, a C–C bond rotation makes it possible that the carbon atom bearing leaving group is easily attacked by the nucleophilic site. Finally, the three‐membered ring compound D is generated by leaving of the onium group (Scheme ) …”

Section: Introductionmentioning

confidence: 99%

Stereoselective aziridination of imines via ammonium ylides: A molecular electron density theory study

Jalali

Hosseini

Ali‐Asgari

et al. 2019

Journal of Heterocyclic Chem

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The highly trans-stereoselective reaction of ammonium salt (AS 2) toward (E)-Nbenzylidene-4-methylbenzenesulfonamide (IM 4) in the presence of Na 2 CO 3 leading to an aziridine derivative, trans-Az 6, was theoretically studied using Molecular Electron Density Theory (MEDT) at the B3LYP/6-31G(d) computational level to probe energy transformation, selectivities, and molecular mechanism. The reaction starts by a nucleophilic substitution reaction between 1,4diazabicyclo [2.2.2]octane (DABCO) and phenacyl bromide (PB) to form AS 2 which undergoes a proton abstraction by Na 2 CO 3 to produce Ammonium Ylide (AY 3). Subsequently, nucleophilic addition of AY 3 to the double bond in IM 4 leads to form a betaine-like intermediate, namely, IN-Ta which named IN-Ta. Finally, trans-Az 6 is produced as a result of the nucleophilic attack of the negatively charged nitrogen atom on the carbon atom bearing DABCO in IN-Ta.Analysis of the relative Gibbs free energies shows that the ring closure step is the rate-determining step (RDS). By an investigation of the conceptual density functional theory, CDFT reactivity indices AY 3 and IM 4 are classified as a strong nucleophilic molecular system and as a strong electrophilic molecular system, respectively, which implies that the addition step of AY 3 to IM 4 has a high polar character. An analysis of the calculated electrophilic and nucleophilic Parr functions at the reactive sites of reagents clarifies the regioselectivity observed experimentally within the C 1 -C 2 bond creation process.

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“…It is worthy to indicate that among the mentioned synthetic routes, the last ones has a prominent place. Ylides, distinguished by a negatively charged carbon atom (a carbanionic site) directly bound to a positively charged heteroatom (the onium group), have received much attention as frequently employed reagents in organic syntheses, especially since the seminal reports of Wittig and co‐workers over the olefination reactions via phosphonium ylides . It is well documented that the reactivity and scope of application of ylides are significantly affected not only by the nature of the onium group but also by the degree of stabilization provided by the substituents at the carbanionic site .…”

Section: Introductionmentioning

confidence: 99%

Aziridination of Aromatic Aldimines Through Stabilized Ammonium Ylides: A Molecular Electron Density Theory Study

et al. 2019

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The domino reaction between ammonium salt AS 4 and aldimine AD 2, in the presence of Cs2CO3, yielding aziridine trans‐AZ 7 was studied within the Molecular Electron Density Theory at the B3LYP (PCM, DCM)/def2‐TZVP//B3LYP (PCM, DCM)/GenECP computational level. This domino reaction begins with the proton abstraction from AS 4 by Cs2CO3 yielding ammonium ylide AY 5. The subsequent nucleophilic attack of AY 5 on AD 2 furnishes the gauche betaine‐like intermediate IN‐2Tg1, which experiences a C–C single bond rotation generating the anti betaine‐like intermediate IN‐2Ta. Finally, IN‐2Ta is converted into trans‐AZ 7 by an SNi process. Analysis of the relative Gibbs free energies indicates that conversion of IN‐2Ta into trans‐AZ 7 is the rate‐determining step. Analysis of the reactivity indices allows characterizing AY 5 as a strong nucleophile and AD 2 as a strong electrophile, in clear agreement with the high polar character of the addition step, while analysis of the electrophilic Parr functions explains the regioselectivity within the C1–C2 single bond formation. A Bonding Evolution Theory study of the bonding changes along the ring‐closure step allows understanding the mechanism of the SNi reaction, which takes place through a non‐concerted two‐stage one‐step mechanism involving zwitterionic species having a carbocationic C1 center.

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Ammonium Ylide Mediated Cyclization Reactions

Cited by 46 publications

References 99 publications

Enantioselective Ammonium Ylide Mediated One‐Pot Synthesis of Highly Substituted γ‐Butyrolactones

Enantioselective Ammonium Ylide Mediated One‐Pot Synthesis of Highly Substituted γ‐Butyrolactones

Stereoselective aziridination of imines via ammonium ylides: A molecular electron density theory study

Aziridination of Aromatic Aldimines Through Stabilized Ammonium Ylides: A Molecular Electron Density Theory Study

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