Combined (R)-2′-amino-3-bromo-5′H-spiro[chromeno[2,3-b]pyridine-5,4′-oxazol]-7-ol (2.259 g, 6.49 mmol), tetrakis(triphenylphosphine)palladium (0.750 g, 0.649 mmol), copper(i) iodide (0.124 g, 0.649 mmol) and THF (26.0 mL, 6.49 mmol) and DMF (26.0 mL, 6.49 mmol) in a reaction tube. Added diisopropylamine (18.19 mL, 130 mmol) then 2-methylbut-3-yn-2-ol (3.17 mL, 32.4 mmol) and flushed the reaction tube with argon. Sealed and heated at 85° C. for 3 hours. The mixture was diluted with water (100 mL) and extracted with DCM (1×100 mL, 2×50 mL). The combined organic extracts were dried over sodium sulfate, filtered, and evaporated. The resuling liquid was poured onto a 25-g SCX-2 column and eluted with methanol. The product was then eluted with 2M ammonia in methanol. The filtrate was evaporated and purified by chromatography on a 120-g Redi-Sep column, eluting with 0-100% of a 90:10:1 mixture of DCM/MeOH/NH4OH in DCM to give (R)-2′-amino-3-(3-hydroxy-3-methylbut-1-ynyl)-5′H-spiro[chromeno[2,3-b]pyridine-5,4′-oxazol]-7-ol as a tan solid.
