As shown in step 6-i of Scheme 6, 2,3-dimethoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (Compound 2021, 920 mg, 3.47 mmol), methyl 4-bromo-2,6-dimethyl-benzoate (844 mg, 3.47 mmol), and Cs2CO3 (2.26 g, 6.94 mmol) were taken up in DMSO (12 mL) in a sealable tube. Nitrogen gas was bubbled through the solution for 5 minutes, dppfPdCl2 (141 mg, 0.174 mmol) added, and the vessel sealed. The reaction mixture was heated at 90° C. for 60 minutes under an atmosphere of nitrogen. After cooling, the mixture was poured into EtOAc/water. The organics were washed with water, brine, passed through a plug of Florisil®, and concentrated under reduced pressure to give a solid. The solid was suspended in MeOH and collected by filtration to provide methyl 4-(5,6-dimethoxy-3-pyridyl)-2,6-dimethyl-benzoate (Compound 2022, 310 mg). The filtrate was concentrated and purified by silica gel chromatography (0 to 50% EtOAc/hex) to provide an additional 400 mg of Compound 2022 (total yield 710 mg, 2.4 mmol, 68% yield). This compound was used in subsequent reactions as is.
