An Uncharged Amine in the Transition State of the Ribosomal Peptidyl Transfer Reaction

The ribosome has an active site comprised of RNA that catalyzes peptide bond formation. To understand how RNA promotes this reaction requires a detailed understanding of the chemical transition state. Here, we report the Brønsted coefficient of the α-amino nucleophile with a series of puromycin derivatives. Both 50S subunit- and 70S ribosome-catalyzed reactions displayed linear free-energy relationships with slopes close to zero under conditions where chemistry is rate limiting. These results indicate that, at the transition state, the nucleophile is neutral in the ribosome-catalyzed reaction, in contrast to the substantial positive charge reported for typical uncatalyzed aminolysis reactions. This suggests that the ribosomal transition state involves deprotonation to a degree commensurate with nitrogen-carbon bond formation. Such a transition state is significantly different from that of uncatalyzed aminolysis reactions in solution

Synthesis of Fluoropyrrolidines and (Fluoroalkyl)pyrrolidines

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Synthèse et réactivité de phosphonodithioacétates fluorés (applications à la synthèse de glycosides, de peptides et de nucléotides modifiés)

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Photocatalyzed Hydroaminodifluoroalkylation of Alkenes

International audienceAbstract The synthesis of undescribed β‐aminodifluoroethylsulfinates and their uses in the hydroaminodifluoroalkylation of alkenes is reported. This reaction is performed in the presence of a photocatalyst (4CzIPN, Ru complexes) and enables the direct incorporation of a β‐difluoroamine moiety into vinylic aryls, unactivated alkenes, and electron‐rich, or ‐deficient alkenes. The mechanism was studied, and the formation of a gem ‐difluoromethyl radical was observed after the selective oxidation of the sulfinate function

Synthesis of Fluorinated and Trifluoromethyl-Substituted Alkenes through the Modified Julia Olefination: An Update

International audienceThe modified Julia olefination is now a powerful tool for the synthesis of a large range of functionalized alkenes. This short review covers the last five years and provides an overview of the synthesis of mono-, difluoro-, and trifluoromethyl-substituted alkenes via the modified Julia olefination focusing on the novel scope of this reaction.1 Introduction2 Monofluoroalkenes2.1 Disubstituted α- and β-Monofluoroalkenes2.2 Bis(trifluoromethyl)phenyl Sulfones2.3 Conjugated Monofluoroalkenes2.4 Intramolecular Julia Olefination2.5 Smiles Rearrangement from Fluorinated Keto Sulfones2.6 Fluoroallylamines2.7 Fluorinated exo-Glycals2.8 Monofluoroalkenes with an α-Stereocenter at the Allylic Position3 1,1-Difluoroalkenes4 Trifluoromethyl-Substituted Alkenes5 Conclusio

Metal‐Free Aminomethylation of Aromatic Sulfones Promoted by Eosin Y

International audienc

Radical conjugate addition of ambiphilic fluorinated free radicals

International audienceThe ambiphilic character of fluorinated radicals was noticed during their radical conjugate addition onto electron-deficient alkenes. Free radicals were trapped with enones when the reaction was conducted from iododifluoro-acetate and -phosphonate derivatives in the presence of Et3B. Competitive addition reaction onto electron-rich or -deficient alkenes was observed depending on the free radical initiator

Preparation of new polyhydroxylated fluoroallylamines

International audienc

Convergent synthesis of functionalized fluoroallylamines by the JuliaeKocienski reaction

International audienceThe synthesis of beta-fluoroallylamines is reported from aminofluorobenzothiazolylsulfones. These open a new route for a short synthesis of vinylic fluoride containing highly functionalized amino residues

In situ Photo-induced formation of a non-stabilized azomethine ylide for the synthesis of fluoropyrrolidines via a 1,3-dipolar cycloaddition

International audienc