6-Cyclopropyl-2,3-di-p-p-tolyl-5H-pyrrolo[2,3-b]pyrazine (step 5) (189 mg, 0.557 mmol) in anhydrous DMF (3 ml) degassed with N2 was treated with NaH (60% in mineral oil) (24.50 mg, 0.612 mmol). After stirring at RT for 30 minutes, ethyl 7-bromoheptanoate (0.119 ml, 0.612 mmol) was added and stirring continued for 2 hours. The mixture was diluted with water (50 ml) and the pH was adjusted to pH 1 using 2M HCl. The resulting mixture was extracted with DCM (×3) and the combined organic extracts were concentrated under reduced pressure. Purification of the crude product by chromatography on silica eluting with 0-10% EtOAc in iso-hexane afforded the titled compound as a yellow oil;
