A solution of 1-(4-chloro-butyl)-5-(2,4-dimethyl-oxazol-5-yl)-1H-pyrimidine-2,4-dione (Prep65, 100 mg, 0.34 mmol), (1S,5R)-1-(4-trifluoromethyl-phenyl)-3-aza-bicyclo[3.1.0]hexane (Prep4, 68 mg, 0.3 mmol), and DIPEA (130 mg, 1 mmol) in absolute EtOH (3 ml) was placed in a microwave oven and irradiated at 130° C. for 3 hours. The solvent was removed under vacuum and the residue was partitioned between water and ethyl acetate. The organic phase was evaporated, the crude dissolved in dichloromethane and treated with PS-isocyanate resin (400 mg) under stirring for 3 h. After filtration, the solvent was evaporated and the crude purified by preparative LC-MS. The residue was loaded over a SCX cartridge eluting with MeOH and the product obtained was treated with 4N HCl in dioxane (1 eq), to give the title compound as a white powder. (43 mg, 24% yield).
