Fluorine-containing amino acids and their derivatives. 3. Stereoselective synthesis and unusual conformational features of threo- and erythro-3-fluorophenylalanine

Abstract

concentrated below 30 °C to give the title compound, 0.79 g (70%).Cbz-Aep(OLi)-Gly(OLi) [18, (aa)i = Gly]. An ethanol solution (30 mL) of 11 [(aa)x = Gly, R = Me, 2.0 g, 5.6 mmol) was mixed with 2 N lithium hydroxide (17 mL). After 24 h at room temperature, the reaction mixture was neutralized with 1 N hydrochloric acid and concentrated below 30 °C. Upon mixing the residue with anhydrous ethanol, the title compound was precipitated as a powder, which was purified by reprecipitation using water and ethanol as dissolving and precipitating solvents, respectively, 1.96 g (52%).H-Gly-Aep(OLi)-Gly(OLi) (23). The tripeptide diester 16a (0.24 g, 0.58 mmol) was hydrogenated using Pd/C (10%, 0.12 g) in ethanol (10 mL) at atmospheric pressure and 25 °C for 1 h. After removal of the catalyst with suction filtration, the filtrate was mixed with 2 N lithium hydroxide (1.7 mL) and allowed to stand at room temperature for 20 h. The hydrolysate was then neutralized with 1 N hydrochloric acid and concentrated to afford the residue, which upon triturating with anhydrous ethanol gave amorphous powder, 0.11 g. The 1H NMR spectrum agreed with the assigned structure of the title compound, but also indicated

Mechanistic Probes for the Epimerization Domain of Nonribosomal Peptide Synthetases

“…Given the mechanistic similarities between the alanine racemase and NRPS epimerization domain, we reasoned that chlorovinylglycine (CVG) 1 and β‐fluorophenylalanine 2 (Scheme ) would serve as promising candidates for the design of mechanism‐based probes of the E domain. To accomplish this, we first synthesized probes 1 and 2 according to previously published procedures …”

Fluorinated amino acids: compatibility with native protein structures and effects on protein–protein interactions

“…17 depicts all phenylalanine variants that have been incorporated in line with the here reviewed studies. The syntheses of the C b fluorinated analogues have been described, 82,83 yet they have never been incorporated into peptides or proteins.…”

Benzophenone Schiff bases of glycine derivatives: Versatile starting materials for the synthesis of amino acids and their derivatives

“…Amino acid e-17a was prepared by ester deprotection with trimethylsilyl iodide followed by mild acid hydrolysis and isolation. 26 Note: A "large scale" reaction means different things to different people and will be used in its loosest terms (15 g to ≥1.8 kg starting material) by this "discovery chemist"! Scheme 3.…”