Thionyl Chloride → (-)-(2S,3S)-[3-chloro-3-(3-methoxyphenyl)-2-methylpentyl]-dimethylamine hydrochloride

Participants

Reaction Steps

According to the '737 patent, tapentadol is prepared by the reaction of (−)-(2S,3S)-1-dimethylamino-3-(3-methoxyphenyl)-2-methylpentan-3-ol hydrochloride with thionyl chloride to produce (−)-(2S,3S)-[3-chloro-3-(3-methoxyphenyl)-2-methylpentyl]-dimethylamine hydrochloride, followed by subsequent removal of the ‘Cl’ substituent by treatment with zinc borohydride, zinc cyanoborohydride or tin cyanoborohydride, to produce (−)-(2R,3R)-[3-(3-methoxyphenyl)-2-methylpentyl]-dimethylamine hydrochloride. The (−)-(2R,3R)-[3-(3-methoxy phenyl)-2-methylpentyl]-dimethylamine hydrochloride is then converted to (−)-(1R,2R)-3-(3-dimethylamino-1-ethyl-2-methylpropyl)-phenol (tapentadol) by reacting with concentrated hydrobromic acid at reflux.

Provenance & Evidence