Two-Component Redox Organocatalyst for Peptide Bond Formation
journal contributionposted on 2022-02-21, 15:34 authored by Handoko, Nihar R. Panigrahi, Paramjit S. Arora
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 acidsthe 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 agentsit 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/organooxidant-recycling strategy to catalyze amide bond formation.
required molecular sievesprotected amino acidshydrogen bonding scaffoldnew method utilizescatalytic cycle centeredtwo significant requirementscoupling agents component redox organocatalystcoupling agentsoptimized methodcomponent organoreductantcatalytic amountsamine couplingstoichiometric amountsstandard monomersspecific synthesissolid phasesoc .situ recycling strategyrecently describedrational designdiselenide catalystdehydrating agentcarboxylic acid15977 ).