Potassium tert-butoxide (0.230 g) was added to a solution of methyl 3-acetylamino-6-nitro-2-[5-(tetrahydropyran-2-yloxy)-pent-1-ynyl]benzoate (Intermediate 23, 0.70 g) in anhydrous N-methyl-2-pyrrolidone (18 mL) and the reaction mixture was heated at 70° C. for 1 hour. After cooling, the mixture was diluted with ethyl acetate, washed with water and brine, dried (MgSO4) and filtered. The filtrate was concentrated in vacuo to give methyl 5-nitro-2-[3-(tetrahydropyran-2-yloxy)-propyl]-1H-indole-4-carboxylate (0.530 g) as a dark orange gum.
