Organocatalysts Derived from Unnatural α‐Amino Acids: Scope and Applications

Abstract

The organocatalytic properties of unnatural aamino acids are reviewed. Post-translational derivatives of natural a-aminoa cids include 4-hydroxy-l-proline and 4amino-l-proline scaffolds, and also prolineh omologues. The activity of synthetic unnatural a-amino acid-based organocatalysts, such as b-alkyl alanines, alanine-based phosphines, and tert-leucine derivatives, are reviewed herein. The orga-nocatalytic properties of unnatural monocyclic,b icyclic, and tricyclicproline derivatives are also reviewed. Severalfamilies of these organocatalystsp ermitthe efficient and stereoselective synthesis of complex natural products. Most of the reviewedo rganocatalysts accelerate the reported reactions through covalent interactions that raise the HOMO (enamine intermediates) or lower the LUMO (iminiumintermediates).Scheme1.Ageneral (simplified) mechanism of addition reactionsbye namine organocatalysis promoted by a-amino acid derivatives.[a] M.

Overview on Multienzymatic Cascades for the Production of Non-canonical α-Amino Acids

“…From the biotechnological and biomedical point of view, NcAAs have found applications as a significant expansion of the building-block repertoire and/or as organocatalysts (Agirre et al, 2019), also in the manufacture of a wide range of pharmaceuticals (Patel, 2013;Narancic et al, 2019), or as linear and cyclic peptides (Blaskovich, 2016;Martin et al, 2018). Some of the commercial applications directly rely on the natural properties of peptide-containing NcAAs, such as several antibiotics.…”

Regulated synthesis of Zr-metal–organic frameworks with variable hole size and its influence on the performance of novel MOF-based heterogeneous amino acid–thiourea catalysts

“…6,[9][10][11][12] In particular, some of these MOFs could provide a suitable reaction environment through control of the aperture of the MOF cavities. 13 Amino acid and its derivatives, which are practical organocatalysts, 14 have been widely used for catalyzing asymmetry organic reactions, such as aldol, Michael addition and Mannich reaction. [15][16][17][18] Given the existence of regularly ordered chiral functionalities to provide high enantioselectivity, amino acids are anchored into the MOF cavities to generate a heterogeneous catalyst.…”

Application of (4R)-aminoproline in peptide engineering: conformational bias and pH-responsiveness revisited

“…22,23 In a number of other studies, the side chain amino group of this amino acid has been used as a functionalization site for attachment of moieties or peptide branching. [24][25][26][27] Due to the presence of the amino/ammonium group in the structure, it has been suggested that Amp can serve as a residue that endows peptides with pH-responsiveness. In a couple of proof-of-principle studies, the effect of the medium acidity has been demonstrated for Amp containing collagen mimicking peptides.…”