N-bromobutanimide → 3-Bromo-1-cyclohexyl-6-tosyl-6H-imidazo[1,5-a]pyrrolo[2,3-e]pyrazine

Participants

Reaction Steps

To a solution of 1-cyclohexyl-6-tosyl-6H-imidazo[1,5-a]pyrrolo[2,3-e]pyrazine (0.27 g, 0.67 mmol, prepared using Q from Preparation #13, Lawesson's reagent, and mercury(II) acetate) in THF (10 mL) at about 0° C. was added a solution of NBS (0.12 g, 0.672 mmol) in THF (2 mL). After about 30 min, the reaction mixture was diluted with EtOAc (20 mL) and saturated aqueous NaHCO3 (20 mL). The organic layer was separated, concd in vacuo, and purified by chromatography on silica gel (40 g) eluting with EtOAc:DCM:heptane (1:1:2) to provide 3-bromo-1-cyclohexyl-6-tosyl-6H-imidazo[1,5-a]pyrrolo[2,3-e]pyrazine (0.27 g 83%) as a tan solid: LC/MS (Table 1, Method a) Rt=3.12 min; MS m/z 473, 475 (1:1) (M+H)+.

Provenance & Evidence