New Stereoconservative Syntheses of β,β,β- and γ,γ,γ-Trifluoro-α-amino, α-Hydroxy, and α-Mercapto Acids and Their Incorporation into a Peptide and Depsipeptide Fragment
New Stereoconservative Syntheses of β,β,β- and γ,γ,γ-Trifluoro-α-amino, α-Hydroxy, and α-Mercapto Acids and Their Incorporation into a Peptide and Depsipeptide Fragment
Syntheses of (R)-4,4,4-trifluoro-2-mercaptobutyric acid from (S)-malic acid via a Mitsunobu reaction and from (rac)-thiomalic acid on enzymatic resolution, using Pseudomonas cepacia (Amano lipase PS), are described. A new method for direct determination of ees for (R)- and (S)-4,4,4-trifluoro-2-mercaptobutyric acid derivatives by HPLC on a polysaccharide phase is disclosed. (C) 2000 Elsevier Science Ltd. All rights reserved.
New Stereoconservative Syntheses of β,β,β- and γ,γ,γ-Trifluoro-α-amino, α-Hydroxy, and α-Mercapto Acids and Their Incorporation into a Peptide and Depsipeptide Fragment
作者:Hartmut Schedel、Wojciech Dmowski、Klaus Burger
DOI:10.1055/s-2000-8198
日期:——
Syntheses of β,β,β- and γ,γ,γ-trifluoro-α-amino, α-hydroxy and α-mercapto acids using hexafluoroacetone as protecting and activating reagent are described. The key step of the syntheses is the transformation of an Ï-carboxy group into a trifluoromethyl group on treatment with sulfur tetrafluoride. The carboxy activated species obtained are suitable for direct incorporation into peptide and depsipeptide fragments. RP-HPLC experiments and Mosher's TMPA method (1H and 19F) demonstrate that the reaction sequence occurs without racemization.