Rapid and scalable synthesis of innovative unnatural α,β or γ-amino acids functionalized with tertiary amines on their side-chainsElectronic supplementary information (ESI) available: General reaction procedures for Cpds 1, 9 and 10 and compound characterization; racemization study. See DOI: 10.1039/c5ob00828j

We report a selective ruthenium catalyzed reduction of tertiary amides on the side chain of Fmoc-Gln-O t Bu derivatives, leading to innovative unnatural α,β or γ-amino acids functionalized with tertiary amines. Rapid and scalable, this process allowed us to build a library of basic unnatural amino acids at the gram-scale and directly usable for liquid- or solid-phase peptide synthesis. The diversity of available tertiary amines allows us to modulate the physicochemical properties of the resulting amino acids, such as basicity or hydrophobicity. We report a selective ruthenium catalyzed reduction of tertiary amides on the side chain of Fmoc-Gln-O t Bu derivatives, leading to innovative unnatural α,β or γ-amino acids functionalized with tertiary amines.