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Insertion of electrophilic species on the structure of small molecule ligands or peptides is a well‐known strategy to increase their binding affinity for the target protein of interest. Among these reactive units, the salicylaldehyde (SA) tag can form remarkably stable imine bonds with the ϵ‐amino group of lysine, a highly frequent residue in proteins. In this work, we describe the optimized synthesis of two new noncoded α‐amino acids, starting from l‐homoserine and featuring the SA tag on the side chain. One of these final compounds was successfully inserted into a model tripeptide through in‐solution synthesis. These building blocks will allow the versatile insertion of the SA tag at suitable position of peptide sequences, opening to a tailored design of Lys‐engaging peptide ligands. [ABSTRACT FROM AUTHOR]

In this paper we report the synthesis of new azabicycloalkane scaffolds, which could be exploited to obtain cRGD-based bioconjugates that may find promising application for targeted drug delivery, theranostic, and general cancer-cell labeling. By exploiting a Hosomi-Sakurai intramolecular allylation reaction we efficiently converted a silylated aldehyde precursor into 7,5-fused lactam scaffolds endowed with an exocyclic double bond. The presence of the vinyl function should make it possible to conjugate bioactive compounds to selectively carry them to tumor sites. The optimized synthetic sequence allows the gram-scale preparation of the target scaffolds in a few steps and good 39% overall yield from readily accessible materials. The high reactivity of the exocyclic olefin moiety was ascertained by performing a Heck coupling reaction with 1-bromo-4-nitrobenzene, which gave the corresponding functionalized derivatives in good (80-91%) yields. [ABSTRACT FROM AUTHOR]