Abstract: The O-desmethylvenlafaxines were prepared from venlafaxine reacted with new demethylation reagents cysteine sodium and sodium penicillamine, respectively. The corresponding yields are 86% and 82%, respectively. Since the synthesis could be fulfilled in a one-pot approach by mixing cysteine sodium salt, sodium penicillamine preparation and venlafaxine demethylation together, the reaction was fairly simplified. The optimal reaction conditions are:N-methyl pyrrolidone as the solvent, reaction temperature of 175 ℃ and the pH value of 9.5 for product to crystallize.

Key words: O-desmethylvenlafaxine, venlafaxine, demethylation, cysteine sodium, sodium penicillamine