Stereoselective synthesis of β,β-diborylalanine (AlaBB) and its incorporation into oligopeptides.

We report the stereoselective synthesis of β,β-diborylalanine (AlaBB), a compact amino acid scaffold designed to introduce a gem-diboronic acid motif as a branched connector in peptides. Pinacol-protected AlaBB derivatives, denoted as AlaBB(pin)2, were prepared from an Ellman imine, incorporated into short peptides, and converted to the corresponding gem-diboronic acid form.