To a solution of 1-[3,3-bis(methyloxy)propyl]-5-(2-fluoro-3-pyridinyl)-2,4(1H,3H)-pyrimidinedione (Prep89, 133 mg, 0.430 mmol) in Tetrahydrofuran (THF) (4 ml) at ambient temperature under an Argon atmosphere, hydrochloric acid 2M solution (0.5 ml, 1.000 mmol) was added and the reaction mixture stirred for 5 h. Volatiles were evaporated at rotary (cold bath) and the residue was taken up with triethylamine (0.240 ml, 1.720 mmol) and 4 ml of THF and the slurry was re-evaporated to dryness. The crude obtained was directly used in the next step without any further purification. It was diluted with Acetonitrile (4.00 ml) and to the mixture was added acetic acid (0.025 ml, 0.430 mmol) followed by (1S,5R)-1-(4-trifluoromethyl-phenyl)-3-aza-bicyclo[3.1.0]hexane (Prep4, 98 mg, 0.430 mmol). The resulting mixture stirred at ambient temperature under an Argon atmosphere for 20 minutes then the mixture was cooled down to 0° C. and sodium triacetoxyboronhydride (137 mg, 0.645 mmol) was added in one portion. The reaction mixture was stirred overnight allowing the Temperature to reach gradually ambient. Reaction mixture was diluted with NaHCO3 saturated solution (5 mL) and extracted with AcOEt (3×20 mL). Combined organics were dried over Na2SO4 and evaporated to dryness to get crude material as thick yellow oil (300 mg) that was purified by SiO2 flash chromatography eluting with AcOEt/NH4OH from 100/0 to 96/4 (TLC Rf=0.35 AcOEt/NH4OH 96/4). Evaporation of the solvent afforded the title compound (190 mg) as white foam.
