A solution of 1-(6-bromonaphth-2-ylsulphonyl)-4-[4-(2-t-butyloxycarbonylaminoimidazol-4-yl)benzoyl]piperazine (174 mg, 0.27 mmol) in dichloromethane (1 ml) and dioxan (4 ml) was treated with a solution of hydrogen chloride in dioxan (4 ml of 4M) and stirred overnight. The resulting solid was isolated by filtration to give crude product (163 mg); this was crystallised from ethanol to give 1-(6-bromonaphth-2-ylsulphonyl)-4-[4-(2-aminoimidazol4-yl)benzoyl]piperazine (120 mg, 77% yield), m.p. 274-275° C., 1H NMR (d6DMSO) 3.0-3.1 ppm (broad s,4H), 3.3-3.7 ppm (broad s,4H), 7.35 ppm (d,2H), 7.45 ppm (s,3H), 7.65 ppm (d,2H), 7.8 ppm (t,2H), 8.2 ppm (t,2H), 8.4 ppm (s,1H), 8.45 ppm (s,1H); microanalysis, found: C, 48.8; H, 4.1; N, 11.8; S, 5.5%; C24H22N5O3BrS. 1.0 HCl. 0.5 H2O requires: C, 49.2; H, 4.1; N, 12.0; S, 5.5%; MS (M+H)+ 540/542.
