Decoration of Coiled-Coil Peptides with N-Cysteine Peptide Thioesters As Cyclic Peptide Precursors Using Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) Click Reaction

Continuous Flow Synthesis of N-Sulfonyl-1,2,3-triazoles for Tandem Relay Cu/Rh Dual Catalysis

The continuous flow synthesis of N-sulfonyl-1,2,3-triazoles, which are convenient reactive azavinyl carbene precursors, for tandem relay Cu/Rh dual catalysis has been developed. Most reactions readily proceeded at 75 °C in a short residence time of 13.09 min in the presence of 2.5 mol % of CuTC. The scope of the reactions was explored by synthesizing diversely functionalized N-sulfonyl and sulfamoyl triazoles in yields ranging from 92 to 98%. To demonstrate the scalability of the process, the reaction was conducted on a 5.4 mmol scale with residence and collection times of 13.09 and 60 min, respectively. Furthermore, a series of controlled experiments were performed to investigate the compatibility of Cu and Rh in a batch or a continuous flow system. Finally, the first integrated flow system using the azavinyl carbene intermediate under the tandem relay Cu/Rh dual catalysis was developed for the synthesis of various cis-diamino enones from alkynes and sulfonyl azides.

Effect of Methionine Sulfoxide on the Synthesis and Purification of Aggregation-Prone Peptides

A two-step synthesis for methionine-containing hydrophobic and/or aggregation-prone peptides is presented that takes advantage of the reversibility of methionine oxidation. The use of polar methionine sulfoxide as a building block in solid-phase peptide synthesis improves the synthesis quality and yields the crude peptide, with significantly improved solubility compared to the reduced species. This facilitates the otherwise often laborious peptide purification by high-performance liquid chromatography. The subsequent reduction proceeds quantitatively. This approach has been optimised with the methionine-rich Tar-DNA-binding protein 43 (307-347), but is also more generally applicable, as demonstrated by the syntheses of human calcitonin and two aggregation-prone peptides from the human prion protein.