A solution of NaOH in water (11 mL of 50 wt. %) was added under vigorous stirring to a solution of (1R)-2-{[(benzyloxy)carbonyl]amino}-1-[(4-cyanophenoxy)-methyl]ethyl methanesulfonate (see step (iv) above; 5.7 g, 14.1 mmol) and tetrabutylammonium hydrogensulfate (0.6 g, 1.7 mmol) in DCM (34 mL). The mixture was stirred for 1 h before water (200 mL) and ether (200 mL) were added. The organic phase was washed with water and then dried. The solvents were evaporated and the resulting residue was purified by chromatography (DCM eluant) to yield 3.0 g (69%) of the sub-title compound.
