Pd(PPh3)4 (0.506 g, 0.438 mmol), (S)-2-amino-7′-bromo-4′-fluoro-5H-spiro[oxazole-4,9′-xanthen]-2′-ol (1.6 g, 4.38 mmol), and 2-(tributylstannyl)pyrazine (2.426 g, 6.57 mmol) were combined in 10 ml of DMF and heated in the microwave at 110° C. for two hours. The solution was diluted with ethyl acetate (50 mL) and washed twice with water. The organic layer was washed with brine and dried over anhydrous sodium sulfate, filtered and concentrated. The product was purified via silica gel column chromatography (RediSep 40 g column) using 10-100% 90/10/1 (CH2Cl2/MeOH/ammonia) in CH2Cl2 to afford (S)-2-amino-4′-fluoro-7′-(pyrazin-2-yl)-5H-spiro[oxazole-4,9′-xanthen]-2′-ol as a white solid. MS m/z=365.0 [M+H].
