Magnesium perchlorate (0.89 g) was added to a solution of 2-[(3-cyclobutyl-2,3,4,5-tetrahydro-1H-3-benzazepin-7-yl)oxy]-5H-pyrrolo[3,4-b]pyridine-5,7(6H)-dione (E233) (0.72 g, 1.98 mmol) in a mixture of chloroform:methanol (1:1; 20 ml) at 0° C. under argon. Sodium borohydride (113 mg) was added and the mixture stirred at for 0.5 h. The mixture was adjusted to pH 2 with HCl (2M), stirred for an additional 0.5 h, then taken to pH11 with sodium hydroxide (2N). The mixture was then extracted with dichloromethane and the combined organic extracts dried (Na2SO4) and evaporated. The residue was purified by column chromatography eluting with a mixture of 0.880 ammonia:methanol:dichloromethane (1:9:90) to afford the title compound (E234); MS (ES+) m/e 366 [M+H]+.
