Treatment of endo-(+)-3-(3-propylsulfonyl-1,2,5-thiadiazol-4-yl)-1-azabicyclo[2.2.1]heptane (I) with sodium hydrosulfide in hot DMF afforded the intermediate thiol (II), which was further condensed with 3-phenyl-2-propyn-1-yl mesylate (III) to yield the corresponding thioether. This compound was finally isolated as the tartrate salt.