A diastereoselective three-component synthesis of chiral 2-(1,2-diaminoalkyl)phenols from an electron-rich phenol, an amine, and a chiral alpha -N,N-dibenzylamino aldehyde is developed. The diastereoselectivity of this phenolic Mannich reaction is temp.-dependent,and either anti or syn diastereomer can be prepd. by controlling the reaction conditions. Low reaction temp. (-20 DegC) favors the formation of anti adduct, whereas higher temp. (60 DegC) under otherwise identical conditions produces mainly the syn isomer. [on SciFinder (R)]