Diversity-oriented synthesis of peptide-boronic acids by a versatile building-block approach.

A new strategy for the synthesis of peptide-boronic acids (PBAs) is presented. 20 Fmoc-protected natural amino acids with orthogonal side-chain protection were straightforwardly converted into their corresponding boron analogues in three simple steps. Subsequent immobilisation on commercially available 1-glycerol polystyrene resin and on-resin transformations yielded a diversity of sequences in high purity.

Virtues of Volatility: A Facile Transesterification Approach to Boronic Acids.

Boronic acids are an increasingly important compound class for many applications, including C-C bond formation reactions, medicinal chemistry, and diagnostics. The deprotection of boronic ester intermediates is frequently a problematic and inefficient step in boronic acid syntheses. We describe an approach that highly facilitates this transformation by leveraging the volatility of methylboronic acid and its diol esters.

Optimization of Cyclic Plasmin Inhibitors: From Benzamidines to Benzylamines.

New macrocyclic plasmin inhibitors based on our previously optimized P2-P3 core segment have been developed. In the first series, the P4 residue was modified, whereas the 4-amidinobenzylamide in P1 position was maintained. The originally used P4 benzylsulfonyl residue could be replaced by various sulfonyl- or urethane-like protecting groups.