AbstractThe synthesis of (R)‐(−)‐ and (S)‐(+)‐2‐amino‐1‐phenylpropane‐3,3,3‐d3via a modification of a published procedure for the unlabelled compounds is described. The preparation of the (S)enantiomer involved in the first step the reduction of D‐phenyl‐alanine to (R)‐2‐amino‐3‐phenyl‐1‐propanol–1,1‐d2with lithium aluminum deuteride. The reduction product was treated with p‐toluenesulfonyl chloride to give (R)‐3‐phenyl–2‐(4‐toluenesulfamoyl)propyl–1,1‐d24‐toluenesulfonate, which was reduced with lithium aluminum deuteride to (S)‐N‐(1‐methyl‐d3‐2‐phenethyl)‐4‐toluenesulfonamide. The latter compound was cleaved to (S)‐(+)‐2‐amino‐1‐phenylpropane‐3,3,3‐d3using naphthalene anion radical. The overall yield in the sequence was 32.8%, the isotopic purity of the product was 99%, and the enantiomeric purity>99%. The