Sodium hydride 80% dispersion in oil (0.10 g) was added portionwise to a solution of 2,4-dioxo-5-phenyl-2,3,4,5-tetrahydro-1H-1,5-benzodiazepine (0.7 g) in dry dimethylformamide (60 ml). The reaction mixture was stirred for 30 min, then a solution of 3,3-dimethylbutylmethanesulphonate (0.575 g) in dry dimethylformamide (3 ml) was added. The reaction mixture was stirred at 90° for 50 min at 23° for 15 h, at 90° for 2h and at 140° for 45 min, then concentrated in vacuo. The residue was diluted with water (30 ml) and brine (20 ml) and extracted with ethyl acetate (150 ml); the organic layer was washed with water (2×50 ml) and brine (50 ml), dried and concentrated in vacuo. The crude product was purified by flash chromatography (eluting with CH-EA 1:1) to give the title compound as a white foam (0.4 g). T.l.c. CH-EA (1:1 ), Rf=0.39.
