A process for the stereoselective preparation of a chiral alcohol or a chiral amine, the process comprising reacting a first prochiral reactant selected from the group consisting of a ketone, an aldehyde, and an imine, with a second reactant comprising a Grignard reagent, in the presence of a chiral trans-diamine of formula (1) as defined herein: Also provided is the use of the chiral trans-diamine of formula (1) in a Grignard reaction and the chiral trans-diamines per se.