NAULET, Guillaume; DELAMARE, Aline; GUICHARD, Gilles; COMPAIN, Guillaume

doi:10.1002/ejoc.202201148

Chimie et Biologie des Membranes et des Nanoobjets [CBMN]

DELAMARE, Aline

Chimie et Biologie des Membranes et des Nanoobjets [CBMN]

GUICHARD, Gilles

Chimie et Biologie des Membranes et des Nanoobjets [CBMN]

Langue

Article de revue

Ce document a été publié dans

European Journal of Organic Chemistry. 2023-03-07, vol. 26, n° 10

Résumé en anglais

We report the direct incorporation of the hexafluoroisobutyl group on a chiral glycine Schiff base complex mediated by 1,8 diazabicyclo[5.4.0]undec-7-ene (DBU). The fluoroalkylation involves 2-(bromomethyl)-1,1,1,3,3,3-hexafluoropropane reagent, which generates in situ hexafluoroisobutylene (HFIB), and reacts then with the enolate through a tandem allylic shift/hydrofluorination process. We showed that the use of neutral organic base DBU generates in situ an original DBU⋅HF salt, which preserves the fluoride nucleophilicity and acts as a fluorinating agent. This fluoride salt promotes the hydrofluorination of the pentafluorinated alkene overcoming the usual fluoride β-elimination observed with α-CF3-vinyl reagents. With alkali metal bases, by contrast, the hydrofluorination is disfavored and the pentafluorinated alkene intermediate is obtained predominantly. This study highlights the critical role of the fluoride counter ion to preserve its nucleophilicity. The protocol is amenable to multidecagram scale synthesis of enantiopure (S)- and (R)-5,5,5,5’,5’,5’-hexafluoroleucine and their N-Fmoc or N-Boc derivatives in good overall yield.< Réduire

Mots clés en anglais

Fluoroalkylation

Fluorination

Amino acids

Stereoselective synthesis

Synthetic methods

URI

https://oskar-bordeaux.fr/handle/20.500.12278/201310

DOI

http://dx.doi.org/10.1002/ejoc.202201148

Project ANR

Interactions supramoléculaires sélectives et directionnelles à base de synthons fluorés hautement polaires - ANR-20-CE06-0008

Unités de recherche

CBMN : Chimie & de Biologie des Membranes & des Nano-objets - UMR 5248

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In Situ Generated DBU⋅HF Acts as a Fluorinating Agent in a Hexafluoroisobutylation Tandem Reaction: An Effective Route to 5,5,5,5’,5’,5’‐Hexafluoroleucine

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Mots clés en anglais

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Unités de recherche