To a solution of 1-cyclohexyl-3-(5-tosyl-5H-pyrrolo[2,3-b]pyrazin-2-yl)propan-1-one (0.050 g, 0.12 mmol) in THF (2 mL) was added 2,4-bis(4-phenoxyphenyl)-1,3-dithia-2,4-diphosphetane-2,4-disulfide (0.071 g, 0.13 mmol, TCI). After about 6 h at ambient temperature, the reaction mixture was diluted with EtOAc (50 mL) and NaHCO3 (50 mL). The organic layer was separated, dried over anhydrous Na2SO4, filtered, and concentrated under reduced pressure. The crude product was purified by chromatography on silica gel eluting with a gradient of 40-90% EtOAc in heptanes to provide 8-cyclohexyl-3-tosyl-3H-dipyrrolo[1,2-a:2;3′-e]pyrazine as a tan solid (0.020 g, 42%). LC/MS (Table 2, Method a) Rt=3.39 min; MS m/z: 394 (M+H)+.
