(6-(2-((tert-Butoxycarbonyl)amino)ethyl)-1,3-dimethyl-2,4-dioxo-2,3,4,6-tetrahydro-1H-pyrrolo[3,4-d]pyrimidin-5-yl)boronic acid (step 4) (631 mg, 1.724 mmol), Pd-118 (commercial, CAS 95408-45-0) (51.1 mg, 0.078 mmol, 5 mol %) and potassium carbonate (433 mg, 3.13 mmol) were suspended in n-butylacetate (11.2 mL). The vessel was evacuated and back filled with N2 (×4). Under a stream of N2 was charged 1-bromo-3-chlorobenzene (commercial) (0.184 mL, 1.567 mmol) and water (0.056 mL, 3.13 mmol). The vessel was heated to 80° C. for 2 hrs under microwave irradiation. An additional amount of water (100 μL) and 1-bromo-3-chlorobenzene (0.184 mL, 1.567 mmol) was charged and the mixture heated to 80° C. for a further 2 hrs under microwave irradiation. The reaction mixture was diluted with water (40 mL) and EtOAc (20 mL) and the layers were separated. The aqueous was extracted with EtOAc (4×20 mL) and the combined organics were washed with brine (20 mL), dried (Na2SO4) and filtered under reduced pressure. Silica gel was added to the solution and the solvent evaporated under reduced pressure. The residue was purified via ISCO SiO2 80 g RediSep® Rf column eluting with 50-70% EtOAc/hexane. The fractions containing product were combined and evaporated to afford a pale tan solid, which was dried under vacuum at 50° C. for 3 hrs. This afforded the title product as a pale tan solid.
