A flask was charged with (6-(5-methoxy-1-methyl-1H-indol-3-yl)-5-((2-(trimethylsilyl)ethoxy)methyl)-5H-pyrrolo[2,3-b]pyrazin-2-yl)methanol (4.00 g, 9.12 mmol, Preparation #F.1), DCM (90 mL) and thionyl chloride (0.732 mL, 10.0 mmol). The mixture was stirred at rt for about 40 min and concentrated under reduced pressure. The residue was dissolved in DMF (90 mL) and treated with NaN3 (1.48 g, 22.8 mmol). The mixture was stirred overnight at rt. The solution was diluted with water (150 mL). The suspension was extracted with EtOAc (3×125 mL). The combined organic layers were dried over anhydrous MgSO4, filtered and concentrated under reduced pressure to give 2-(azidomethyl)-6-(5-methoxy-1-methyl-1H-indol-3-yl)-5-((2-(trimethylsilyl)ethoxy)methyl)-5H-pyrrolo[2,3-b]pyrazine (4.23 g, 100%): LC/MS (Table 2, Method b) Rt=3.16 min; MS m/z 464 (M+H)+.
