This tutorial review provides an introduction to the synthesis and characterization of chiral-at-metal complexes and their catalytic application in organic transformations. The synthetic access to these architectures either via chiral resolution or by employment of chiral ligands is described, characterization techniques for the complexes are referenced and the application of the R/S nomenclature is explained. Racemization and epimerization processes are often observed for the title compounds; the article gives mechanistic insights to these processes and describes how to recognize and document them. Finally, key catalytic applications in organic synthesis are presented and how the molecular architectures of the chiral-at-metal complexes lead to stereodifferentiation and, thus to enantiomeric excesses in the products.

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The scope of CCC-NHC pincer complex synthetic methodology by metalation/transmetalation has been extended to Ir. Structural characterization revealed that it is isomorphous with the Rh complex. Both Rh and Ir complexes are efficient catalysts for the hydroamination/cyclization of secondary amines in the presence of air and/or water.

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Propargylic alcohols are valuable starting materials in organic synthesis; they are easily accessible and can be functionalized further, either through the triple bond or the alcohol functionality. Certain transition metals such as ruthenium or gold have an affinity for propargylic alcohols or alkyne units, which allows for catalytic activation of these substance classes. This review article provides a survey of various transition-metal-catalyzed functionalizations of propargylic alcohols with an emphasis on the latest literature. Examples of nucleophilic propargylic substitution reactions, allene formation, addition and coupling reactions, cyclization reactions, Meyer-Schuster, Rupe and redox-isomerization reactions are given in the article, along with the scope and limitations of the corresponding transformations and mechanistic considerations.

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