Efficient Synthesis of the Peptide Fragment of the Natural Depsipeptides Jaspamide and Chondramide

First Phosphonic-Type Inhibitors and Activity-Based Probes Specific to the O'nyong-nyong Virus Capsid Protease

The O'nyong-nyong virus (ONNV) is a member of the Alphavirus genus isolated for the first time in 1959 in Gulu (Uganda). The main symptoms of O'nyong-nyong fever are nonspecific and flu like; a proper diagnosis at the early stage is challenging. Until today, the first ONNV epidemic in 1959-1962 remains one of the largest arbovirus outbreaks ever recorded (over 2 million cases). No specific therapy is available thus far. Capsid protease (CP) is a chymotrypsin-like serine protease that catalyzes the autoproteolytic maturation of the structural polyprotein and undergoes self-inactivation upon the release of the mature capsid (C) protein. Despite the discovery of this virus more than 60 years ago, many aspects of CP remain understudied, including substrate specificity. Herein, the structures of the first phosphonic-type inhibitors and activity-based probes specific to the ONNV CP are presented.

Recent developments in the total synthesis of natural products using the Ugi multicomponent reactions as the key strategy

The total syntheses of selected natural products using different versions of the Ugi multicomponent reaction is reviewed on a case-by-case basis. The revision covers the period 2008-2023 and includes detailed descriptions of the synthetic sequences, the use of state-of-the-art chemical reagents and strategies, as well as the advantages and limitations of the transformation and some remedial solutions. Relevant data on the isolation and bioactivity of the different natural targets are also briefly provided. The examples clearly evidence the strategic importance of this transformation and its key role in the modern natural products synthetic chemistry toolbox. This methodology proved to be a valuable means for easily building molecular complexity and efficiently delivering step-economic syntheses even of intricate structures, with a promising future.

Chiral β3-isocyanopropionates for multicomponent synthesis of peptides and depsipeptides containing a β-amino acid fragment

An efficient three-step synthesis of a novel family of enantiomerically pure isocyanides derived from β3-isocyanopropionic acids was elaborated. Easily available N-formylated α-amino acids were used as starting materials towards this aim. The 3-step sequence (Arndt-Eistert reaction-Wolff rearrangement-dehydration) resulted in target isonitriles in good yields (up to 97%). As a result a new family of isocyanides bearing a fragment of β3-amino acids with different functional groups (amides, esters and short peptides) was obtained. It was demonstrated that these new isonitriles can be used in the Ugi and Passerini reactions to prepare short peptides and depsipeptides having a β-amino acid fragment incorporated.