Efficient gold(I) catalysed asymmetric hydroamination of alkenes
The hydroamination of alkenes is an atom-economical chemical reaction which allows the direct synthesis of various cyclic or acyclic amines of interest. However, because harsh reaction conditions are generally required, gold catalysed hydroamination of alkenes has been scarcely applied for the synthesis of chiral amines. Recent publications in this field are highlighted in order to underline the usefulness of some readily available gold catalysts for the asymmetric hydroamination of alkenes in inter- and intramolecular fashions using mild reaction conditions.
Amines are ubiquitous in natural products, building blocks and targets for fine chemicals, farming-related chemicals and compounds of pharmaceutical interest. Catalysis can offer highly selective and atom-economic reactions but challenges remain for some reactions like hydroamination which is the shortest synthetic route to secondary and tertiary amines (1). For the enantioselective synthesis of optically pure amines, the most studied and privileged hydroamination method is metal-catalysis. Lanthanides and actinides (f-block), group 4 metal (Zr, Ti) and main-group metal (Mg, Li) complexes led to significant achievements, mainly for intramolecular reactions (1a-b, e). By comparison, applications in asymmetric catalysis of transition metals from groups 3-11 (d-block) remain scarce but offer a broader functional group tolerance and substrate scope (1b,e). Moreover, the development of recoverable catalysts may favour these metals which can lead to stable and easy to handle organometallic catalysts (1e). Recently, the usefulness of gold for N-H addition was pointed out on alkyne (1a,c, 2a), alkene (2b-c), allene (2d) and diene (2b,e) substrates f ...