To a solution of potassium phosphate, tribasic (0.564 g, 2.66 mmol), potassium phenyltrifluoroborate (0.245 g, 1.330 mmol), and 8-chloro-2-methyl-3-oxo-3,4-dihydro-2H-benzo[b][1,4]oxazine-6-carbaldehyde 15 (0.2 g, 0.886 mmol) in toluene (Ratio: 4.00, 16 mL) and water (Ratio: 1.000, 4.0 mL) was added PdOAc2 (0.015 g, 0.066 mmol) and dicyclohexyl(2′,6′-diisopropoxybiphenyl-2-yl)phosphine (0.062 g, 0.133 mmol) at 23° C. The reaction was stirred at 115° C. for 42 hr. The reaction mixture was poured into water (2 mL) and extracted with Et2O (3×5 mL). The organic layer was dried over Na2SO4, filtered, and the organic phase stripped to dryness via rotary evaporation. The resulting crude material was purified via medium pressure chromatography using a gradient eluant of CH2Cl2/MeOH. The appropriate fractions were combined and concentrated via rotary evaporation. The impure material was reconstituted in DMSO (1.0 mL) and purified via preparative mass trigger LCMS using a gradient eluant of 45-70% ACN:0.05% TFA (aq). The early fractions were combined and the solvent was removed via rotary evaporation. The purified product was dried in vacuo to provide the title compound as an off-white solid (0.0459 g, 0.172 mmol, 19.37% yield). 1H NMR (400 MHz, DMSO-d6) δ ppm 1.44 (d, J=6.82 Hz, 3H) 4.85-4.92 (m, 1H) 7.38-7.43 (m, 2H) 7.46-7.51 (m, 2H) 7.57-7.62 (m, 2H) 7.64 (d, J=2.02 Hz, 1H) 9.91 (s, 1H) 11.04 (s, 1H). ESI-MS: m/z 268.1 (M+H)+.
