A glass microwave reaction vessel was charged with (S)-2-amino-5′-fluoro-2′-(2-fluoropyridin-3-yl)-5H-spiro[oxazole-4,9′-xanthene]-7′-yl trifluoromethanesulfonate (120 mg, 0.234 mmol), trans-dichlorobis(triphenyl-phosphine)palladium (19.69 mg, 0.028 mmol), triphenylphosphine (36.8 mg, 0.140 mmol), lithium chloride (0.041 mL, 1.987 mmol) and (E)-tributyl(2-(3-methyloxetan-3-yl)vinyl)stannane (136 mg, 0.351 mmol). DMF (2.5 mL) was added and the reaction mixture was purged with argon for several minutes. The vessel was sealed and heated in a Initiator microwave reactor (Personal Chemistry, Biotage AB, Inc., Upssala, Sweden) at 120° C. for 10 mins. The mixture was cooled to rt and portioned between saturated KF (7 mL) and CH2Cl2 (20 mL). The organics were washed with brine, dried over sodium sulfate filtered and concentrated. The crude material was absorbed onto a plug of silica gel and purified by chromatography through a Redi-Sep pre-packed silica gel column (40 g; 0-50% ethyl acetate in hexanes then 50% CH2Cl2: MeOH: NH4OH in EtOAc) to provide (S,E)-4′-fluoro-7′-(2-fluoropyridin-3-yl)-2′-(2-(3-methyloxetan-3-yl)vinyl)-5H-spiro[oxazole-4,9′-xanthen]-2-amine as light-yellow solid. MS m/z=462.2 [M+H].
