Access to Saturated Aza‐Heterocycles using the Borrowing Hydrogen Methodology.

Borrowing hydrogen (BH) has reached a wide attention from the chemistry community as a new opportunity to construct efficiently C−N bond (as well as C−C or C−S bond). This straightforward strategy is usually supported by relevant organometallic catalysts, involved in the dehydrogenation‐reduction processes. This concept highlights specifically the application of the borrowing hydrogen to the preparation of saturated aza‐heterocycles (piperidines, pyrrolidines and piperazines) extensively present in high‐added value molecules of pharmaceutical industry over the last 40 years using homogenous catalysis in particular. A focus will be given to the appropriate metals (Ru, Ir and more recently earth‐abundant metals) used for this transformation. An extension to chiral induction in order to prepare enantiopure N‐heterocycles will be also reported. [ABSTRACT FROM AUTHOR]