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). 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). (DCM was used because this product is partially soluble in water and EtOAc is not as good a solvent for it). The combined organic extracts were dried over sodium sulfate, filtered, and evaporated. The resulting 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.
