Ethyl 3-oxo-piperazine-1-carboxylate (161.4 g, 937.2 mmol), copper(I) iodide (27.65 g, 145.20 mmol) and potassium phosphate (tribasic, n-hydrate) (205.1 g, 937.2 mmol) is charged into a glass reactor at room temperature under nitrogen. A solution of 3-bromo-1-methyl-6-(pyridin-2-ylmethoxy)-1H-pyrrolo[2,3-b]pyridine (210 g, 660.0 mmol) in 1,4-dioxane (2.73 L) is added, followed by N,N′-dimethylethane-1,2-diamine (24.34 g; 270.6 mmol). The reaction mixture is heated to 100° C. and stirred for 20 h. Further copper(I) iodide (10.06 g, 52.80 mmol) and N,N′-dimethylethane-1,2-diamine (10.95 g, 105.6 mmol) is added and the reaction stirred for a further 23 h. The reaction mixture is combined with a smaller batch made in a similar manner starting with 23.68 g of 3-bromo-1-methyl-6-(pyridin-2-ylmethoxy)-1H-pyrrolo[2,3-b]pyridine. The mixture is cooled to room temperature, then poured into water (4.2 L) and extracted with EtOAc (3×1.7 L). The organic extracts are combined and washed with 3% w/w aqueous ammonia (3×400 mL), then water (2×2 L), then brine (600 mL), and dried over sodium sulphate, filtered and concentrated in vacuo. The residue is purified by column chromatography on silica, eluting with 50 to 100% EtOAc in isohexane. The appropriate fractions are combined, evaporated and recrystallized from ethanol (525 mL). The solid is dried to give the title compound (125.6 g, 0.3 mol). MS (m/z): 410.1 (M+1). 1H-NMR (400 MHz, CDCl3): δ 1.31 (t, 3H), 3.72 (s, 3H), 3.80-3.78 (t, 2H), 3.86 (t, 2H), 4.22 (q, 2H), 4.34 (s, 2H), 5.59 (s, 2H), 6.71 (d, 1H), 7.01 (s, 1H), 7.20 (dd, 1H), 7.49 (d, 1H), 7.70-7.66 (m, 2H), 8.60 (d, 1H). DSC (onset) mp=143.42° C.
