A brown solution of Intermediate 26a (94.2 mg, 0.263 mmol), Intermediate 34c (90.6 mg, 0.250 mmol), and DIPEA (0.054 mL, 0.31 mmol) in dry dioxane (3 mL) was stirred at 75° C. for 16 h. The cooled solution was concentrated in vacuo, suspended in water (3 mL) and extracted with DCM (2×3 mL). The combined organics were passed through a hydrophobic frit and concentrated in vacuo to leave a dark brown oil. Flash chromatography (silica gel, 3-9% MeOH in DCM) gave a pale yellow solid. MDAP (Method 7) gave an off-white solid (72 mg, 50%). LCMS (Method 5): Rt 3.98 min, m/z 572.4 [MH+].
