Stereospecific substitution at α‐carbon to trifluoromethyl group: Application to optically active fluorinated amino acid syntheses

Katagiri, Toshimasa

doi:10.1002/chir.10160

Cited by 24 publications

(6 citation statements)

References 62 publications

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“…Trifluoromethyl groups (−CF 3 ) could facilitate this since there is a large electrostatic repulsion between −CF 3 groups or between −CF 3 groups and aromatic rings . This repulsion is the result of high electron density around trifluoromethyl groups originating from the strong electronegativity of fluorine atoms. − …”

mentioning

confidence: 99%

Structural Distortion and Bandgap Increase of Two-Dimensional Perovskites Induced by Trifluoromethyl Substitution on Spacer Cations

Wang

Najarian

Hao

et al. 2020

J. Phys. Chem. Lett.

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In further advancing display technologies, especially for improved blue emitters, to engineer the bandgap of promising semiconductors such as hybrid perovskites is important. Present-day methods for tuning the bandgaps of perovskites, such as the incorporation of mixed halide anions, suffer drawbacks such as phase separation and difficulty in synthesis. Here we report a new 2D lead iodide perovskite that emits in the blue spectral region. We exploit an increased angular distortion of PbI 4 2− octahedra to widen the bandgap of 2D metal halide perovskites. We synthesized 2D lead iodide perovskites based on (4-Y-C 6 H 4 CH 2 NH 3 ) 2 PbI 4 (Y = H, F, Cl, Br, I) and substituted the halogen atoms with a −CF 3 group to create (4-CF 3 -C 6 H 4 CH 2 NH 3 ) 2 PbI 4 compounds. We observed that the CF 3 -substituted material exhibited a ∼0.16 eV larger bandgap than did the halogen-substituted materials. We used X-ray diffraction and density functional theory simulations and found that the blue shift can be assigned to the angular distortion of the PbI 4 2− lattice, a distortion traceable to repulsive intermolecular interactions between the trifluoromethyl groups on oppositely-arranged spacers. These results add a degree of freedom in tuning 2D perovskites to selected bandgaps for optoelectronic applications.

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confidence: 99%

Structural Distortion and Bandgap Increase of Two-Dimensional Perovskites Induced by Trifluoromethyl Substitution on Spacer Cations

Wang

Najarian

Hao

et al. 2020

J. Phys. Chem. Lett.

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“…Several reviews have been published that summarize synthetic methodologies to a broad variety of fluorine containing amino acids. [20][21][22][23][24][25][26] The scope of this review is to give an overview on the synthetic repertoire available for the construction of aTfm and aDfm substituted amino acids.…”

Section: Klausmentioning

confidence: 99%

Synthetic strategies to α-trifluoromethyl and α-difluoromethyl substituted α-amino acids

et al. 2008

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The combination of the unique physical and chemical properties of fluorine with proteinogenic amino acids represents a new approach to the design of biologically active compounds including peptides with improved pharmacological parameters. Therefore, the development of routine synthetic methods which enable the effective and selective introduction of fluorine into the desired amino acids from readily available starting materials is of significant synthetic importance. The scope of this critical review is to summarize the most frequently employed strategies for the synthesis of alpha-difluoromethyl and alpha-trifluoromethyl substituted alpha-amino acids (114 references).

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“…This indicates that the rate-diminishing effect of sulfonyl-and trifluoroalkyl groups is probably due to steric or electrostatic effects [164,169,183], which are only active in close proximity to these groups and disappear in the corresponding vinylogous electrophiles. It has also been proposed that the Sn2-inhibiting effect of the trifluoromethyl group is because of electrostatic repulsion between the nucleophile and the partial negative charge on the fluorine atoms [184].…”

Section: 35mentioning

confidence: 99%

Aliphatic Nucleophilic Substitutions: Problematic Electrophiles

Dörwald

2004

Side Reactions in Organic Synthesis

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Nucleophilic substitutions at sp 3 -hybridized carbon are among the most useful synthetic transformations, and have been thoroughly investigated [1][2][3]. The success of these reactions depends mainly on the structures of the nucleophile and electrophile, their concentration, and on the solvent and reaction temperature chosen. The structure of the electrophile in nucleophilic substitutions is of critical importance, because many unwanted side reactions result from unexpected reactivity of the electrophile.In Scheme 4.1 the mechanisms of typical monomolecular (Sn1) and bimolecular (Sn2) nucleophilic substitutions at a neutral electrophile with an anionic nucleophile are sketched. Sn1 reactions usually occur when the electrophile is sterically

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Stereospecific substitution at α‐carbon to trifluoromethyl group: Application to optically active fluorinated amino acid syntheses

Cited by 24 publications

References 62 publications

Structural Distortion and Bandgap Increase of Two-Dimensional Perovskites Induced by Trifluoromethyl Substitution on Spacer Cations

Structural Distortion and Bandgap Increase of Two-Dimensional Perovskites Induced by Trifluoromethyl Substitution on Spacer Cations

Synthetic strategies to α-trifluoromethyl and α-difluoromethyl substituted α-amino acids

Aliphatic Nucleophilic Substitutions: Problematic Electrophiles

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