¹⁹F NMR as a tool in chemical biology

• Diana Gimenez,
• Aoife Phelan,
• Cormac D. Murphy and
• Steven L. Cobb

Beilstein J. Org. Chem. 2021, 17, 293–318, doi:10.3762/bjoc.17.28

• to detect the presence of a sharp singlet in the 19F NMR spectrum even at nanomolar peptide concentrations. It is worth noting here that, as recently reviewed in detail by Koksch [18][19], while some perfluorinated amino acids such as hexafluoroleucine (12, Figure 1) and pentafluorophenylalanine (13

Synthesis of purines and adenines containing the hexafluoroisopropyl group

• Viacheslav Petrov,
• Rebecca J. Dooley,
• Alexander A. Marchione,
• Elizabeth L. Diaz,
• Brittany S. Clem and
• William Marshall

Beilstein J. Org. Chem. 2020, 16, 2739–2748, doi:10.3762/bjoc.16.224

• relatively short list: the reduction of the OH group of the C(CF3)2OH moiety (this protocol was employed in the synthesis of enantiomerically pure (S)-5,5,5,5',5',5'-hexafluoroleucine [1]); the Wittig reaction of Ph3P=C(O)C(O)OR with hexafluoroacetone, followed by the hydrogenation of the CH=C(CF3)2 unit

Position-dependent impact of hexafluoroleucine and trifluoroisoleucine on protease digestion

• Susanne Huhmann,
• Anne-Katrin Stegemann,
• Kristin Folmert,
• Damian Klemczak,
• Johann Moschner,
• Michelle Kube and
• Beate Koksch

Beilstein J. Org. Chem. 2017, 13, 2869–2882, doi:10.3762/bjoc.13.279

• this study when positioned N-terminal to the cleavage site. These results provide valuable information for the application of fluorinated amino acids in the design of proteolytically stable peptide-based pharmaceuticals. Keywords: fluorinated amino acids; hexafluoroleucine; peptide drugs; protease

• proteolytic degradation in particular. Meng and Kumar reported that the incorporation of 5,5,5,5’,5’,5’-hexafluoroleucine (HfLeu) into the antimicrobial peptides magainin 2 amide and buforin enhanced their resistance towards proteolytic degradation by trypsin [23]. They also introduced HfLeu into the glucagon

• ). All experiments were performed in triplicate. (a) Structures of isoleucine (1), leucine (2), and their fluorinated analogues 5,5,5-trifluoroisoleucine (3, TfIle) and 5,5,5,5’,5’,5’-hexafluoroleucine (4, HfLeu). The van der Waals volumes given in parentheses correspond to the side chains (starting at α

Synthesis of enantiomerically pure (2S,3S)-5,5,5-trifluoroisoleucine and (2R,3S)-5,5,5-trifluoro-allo-isoleucine

• Holger Erdbrink,
• Elisabeth K. Nyakatura,
• Susanne Huhmann,
• Ulla I. M. Gerling,
• Dieter Lentz,
• Beate Koksch and
• Constantin Czekelius

Beilstein J. Org. Chem. 2013, 9, 2009–2014, doi:10.3762/bjoc.9.236

• be essential factors for secondary structure formation, we compared 5-F3Ile with previously studied (2S,3S)-4’-F3Ile [13], as well as with (S)-5,5,5,5’,5’,5’-hexafluoroleucine (F6Leu), which was prepared according to procedures reported by Keese and coworkers [25]. By plotting their side chain van