Amide bonds are ubiquitous in peptides, proteins, pharmaceuticals, and polymers. The formation of amide bonds is a straightforward process: amide bonds can be synthesized with relative ease because of the availability of efficient coupling agents. However, there is a substantive need for methods that do not require excess reagents. A catalyst that condenses amino acids could have an important impact by reducing the significant waste generated during peptide synthesis. We describe the rational design of a biomimetic catalyst that can efficiently couple amino acids featuring standard protecting groups. The catalyst design combines lessons learned from enzymes, peptide biosynthesis, and organocatalysts. Under optimized conditions, 5 mol % catalyst efficiently couples Fmoc amino acids without notable racemization. Importantly, we demonstrate that the catalyst is functional for the synthesis of oligopeptides on solid phase. This result is significant because it illustrates the potential of the catalyst to function on a substrate with a multitude of amide bonds, which may be expected to inhibit a hydrogen-bonding catalyst.

Herein, the design of a catalyst that combines lessons learned from peptide biosynthesis, enzymes, and organocatalysts is described. The catalyst features a urea scaffold for carbonyl recognition and elements of nucleophilic catalysis. In the presence of 10 mol % of the organocatalyst, the rate of peptide bond formation is accelerated by 10000-fold over the uncatalyzed reaction between Fmoc-amino acid thioesters and amino acid methyl esters.

We report a diaryldiselenide catalyst for cross-dehydrogenative nucleophilic functionalization of hydrophosphoryl compounds. The proposed organocatalytic cycle closely resembles the mechanism of the Atherton–Todd reaction, with the catalyst serving as a recyclable analogue of the halogenating agent employed in the named reaction. Phosphorus and selenium NMR studies reveal the existence of a P–Se bond intermediate, and structural analyses indicate a stereospecific reaction.

Peptides are fundamental therapeutic modalities whose sequence-specific synthesis can be automated. Yet, modern peptide synthesis remains atom uneconomical and requires an excess of coupling agents and protected amino acids for efficient amide bond formation. We recently described the rational design of an organocatalyst that can operate on Fmoc amino acidsthe standard monomers in automated peptide synthesis (J. Am. Chem. Soc. 2019, 141, 15977). The catalytic cycle centered on the conversion of the carboxylic acid to selenoester, which was activated by a hydrogen bonding scaffold for amine coupling. The selenoester was generated in situ from a diselenide catalyst and stoichiometric amounts of phosphine. Although the prior system catalyzed oligopeptide synthesis on solid phase, it had two significant requirements that limited its utility as an alternative to coupling agentsit depended on stoichiometric amounts of phosphine and required molecular sieves as dehydrating agent. Here, we address these limitations with an optimized method that requires only catalytic amounts of phosphine and no dehydrating agent. The new method utilizes a two-component organoreductant/organooxidantrecycling strategy to catalyze amide bond formation.