Carbonation of phenyl lithium with 14CO2 followed by reduction of [14CO2] benzoic acid, led to [α‐14C] benzyl alcohol 3, the oxidation of which afforded the [α‐14C] benzaldehyde 4. The latter, then condensed with pivoylamide 6 (trimethyl acetamide‐N‐(2‐lithio‐4chlorophenyl) gave 5‐chloro‐2 (t‐Butylamide)‐α‐phenyl‐[‐α‐14C] benzyl alcohol 7 which was then oxidized to ketone 8 which it self were subsequently hydrolysed to 5‐chloro‐2‐amino‐[‐α‐14C]benzophenone 9. Grignard reaction of 9 with methylmagnesium iodide gave 5‐chloro‐2‐amino‐α‐methyl‐α‐phenyl‐[‐α‐14C] benzyl alcohol 10. Treatment of the alcohol 10 with ethylthioisocyanate, followed by cyclisation led to 6‐chloro‐2‐(ethylamino)‐4‐methyl‐4‐phenyl‐[‐4‐14C]‐4H‐3,1 benzoxazine 12. The latter was acidified to give rise to Etifoxine hydrochloride 13 in an overall yield of about 31% based on [14C] barium carbonate. © 1997 John Wiley & Sons, Ltd.