To a solution of intermediate 1-[2-(4-cyanophenoxy)ethyl]-1-(2-hydroxy-ethyl)urea (4.7 g, 0.0188 mol; see step (i) above) in dry THF (150 mL) was added n-butyllithium (18.89 mL, 1.1 M) at −78° C. The reaction mixture was stirred at −78° C. for 1 h, after which a solution of freshly crystallised p-toluenesulfonyl chloride (4.3 g, 0.023 mol) in THF (50 mL) was added dropwise. The reaction mixture was then stirred at −78° C. for a further 30 min, before being warmed to −30° C., and stirred for 2 h more. The reaction mixture was quenched with water and extracted with ethyl acetate. The organic layer was washed with brine, dried over Na2SO4, concentrated and the residue was recrystallised in ethyl acetate/hexane to yield the title compound as an off-white solid. Yield: 3.5 g.
