A solution of 3-(3-chloro-1,2,5-thiadiazol-4-yl)-1-azabicyclo[2.2.2]octane (Compound 8) (420 mg, 1.83 mmol), sodiumhydrogen sulfide monohydrate (245 mg, 3.70 mmol) and potassium carbonate (780 mg, 5.64 mmol) in DMF (20 ml) was stirred at room temperature for 2 h. A solution of 1-bromo-3-methylbutane (420 mg, 2.75 mmol) in DMF (5 ml) was added, and the reaction mixture was stirred at room temperature for 3 h. Water (20 ml) was added and the mixture was extracted with ethyl acetate (3×100 ml). The combined extract was washed with brine, dried (MgSO4), filtered and evaporated. The residue was purified by column chromatography (eluent: CH2Cl2 :MeOH:NH4OH (8:2:0.5%)) to give the free base of the desired product in 400 mg yield. Crystallization of the residue with fumaric acid from isopropanol/ether gave the title compound in 370 mg yield. (Compound 99). M.p. 130° -132° C.
