Preparation of methadone and some congeners labeled with tritium in the aromatic rings

[diphenyl‐2,2′‐ 3 H 2 ]Methadone with specific activity of 8‐30 Ci/mmol was prepared by reductive dehalogenation of 6‐dimethylamino‐4, 4‐bis(2‐chlorophenyl)‐3‐heptanone with carrier‐free tritium gas. The labeled congeners (−)‐α‐acetylmethadol, (−)‐α‐acetyl‐N‐normethadol, and (−)‐α‐acetyl‐N,N‐dinormethadol were prepared from (+)‐[diphenyl‐2,2′‐ 3 H 2 ]methadone.