The ruthenium-catalyzed azide alkyne cycloaddition (RuAAC) affords 1,5-disubstituted 1,2,3-triazoles in one step and complements the more established copper-catalyzed reaction providing the 1,4-isomer. The RuAAC reaction has quickly found its way into the organic chemistry toolbox and found applications in many different areas, such as medicinal chemistry, polymer synthesis, organocatalysis, supramolecular chemistry and the construction of 2 electronic devices. This review discusses the mechanism, scope and applications of the RuAAC reaction, covering the literature during the last 10 years. CONTENTS

Hydrogen borrowing provides an efficient and atom economical method for carbon−nitrogen and carbon− carbon bond formation from alcohol precursors. Glycerol is a renewable nontoxic polyol and a potential precursor to small functional organic molecules. We here report the direct amination of solketal, a 1,2-hydroxy-protected derivative of glycerol, via ruthenium-catalyzed hydrogen borrowing, affording up to 99% conversion and 92% isolated yield using [Ru(pcymene)Cl 2 ] 2 as the catalyst precursor. The synthesis of an antitussive agent in 86% overall yield from solketal was also demonstrated using this methodology.

Eight chiral triazoles, for use as peptidomimetic building blocks, were prepared using the ruthenium-catalyzed click (RuAAC) reaction and their conformational properties evaluated by quantum chemistry.

A novel electron poor protection group for amines has been developed. It undergoes rapid cleavage by SmI2-Et3N-H2O and its orthogonality towards the regular benzyl carbamate group (CBz) under reductive or transfer hydrogenolytic conditions is reported.