To a solution of the compound of Preparation 6 (152.0 g, 0.6 mol) in tetrahydrofuran (600 ml) was added concentrated hydrochloric acid (75 ml). The reaction mixture was stirred for 2 h and then poured into water (700 ml). The mixture was filtered, washing through with water (750 ml), and the solid material was dried overnight at 40°C. to give the title compound (156.0 g). 2-Oxo-1-benzimidazolinebutyric Acid, yield (156.0 g). 1H-NMR (d6-DMSO): 1.80-1.89 (2H), 2.20-2.25 (2H), 3.74-3.82 (2H), 6.96-7.01 (3H), 7.05-7.10 (1H)
