To a mixture of the amidine of step 2 (10 g, 52.41 mmol) and sodium bicarbonate (8.6 g, 103 mmol) in isopropanol (1200 ml), 3-bromo-1,1,1-trifluoroacetone (10 g, 52 mmol) was added. After heating at reflux for 22 hours, the reaction mixture was cooled and filtered. The residue was dissolved in methylene chloride and washed water than brine. The organic extracts were dried (MgSO4), filtered and concentrated. The crude mixture was purified by chromatography (silica gel, 100% ethyl acetate) to give. the desired dihydro-imidazole (5.1 g): Anal Calc'd. for C17H16N3SOF3: C, 55.58; H, 4.39; N, 11.44. Found: C, 55.54; H, 4.35; N, 11.20.
