Methods for preparing O-desmethylvenlafaxine

Abstract

The present invention provides an efficient method of making O-desmethylvenlafaxine.

What is claimed:  
     
         1 . O-desmethylvenlafaxine prepared by reacting venlafaxine with a high molecular weight alkane or arene thiolate anion in an alcohol, ethylene glycol, ether of ethylene glycol, or mixture thereof, wherein the O-desmethylvenlafaxine contains no more than about 1% venlafaxine as an impurity.  
     
     
         2 . O-desmethylvenlafaxine prepared by demethylating venlafaxine with dodecyl thiolate and polyethylene glycol 400 in the presence of sodium methylate in methanol at about 180 C to about 200 C for about 2 to about 5 hours and neutralizing the product to about pH 9.5 in the presence of isopropanol, wherein the O-desmethylvenlafaxine contains no more than about 1% venlafaxine as an impurity.