Cesium carbonate → (S)-2-(2-amino-2'-(pyridin-3-yl)-5H-spiro[oxazole-4,9'-xanthene]-7'-yloxy)benzonitrile

Participants

Reaction Conditions

Reaction Steps

A vial was charged with (R)-2-amino-2′-bromo-5H-spiro[oxazole-4,9′-xanthen]-7′-ol (210 mg, 0.605 mmol), cesium carbonate (237 mg, 0.726 mmol), and DMF (4033 μL). The mixture was stirred for 15 min, then 2-fluorobenzonitrile (81 μL, 0.665 mmol) was added. The mixture was heated at 85° C. overnight. The reaction was diluted with water and EtOAc. The aqueous layer was extracted with EtOAc (2×). The combined organic extracts were dried over sodium sulfate, filtered, and evaporated. The residue was chromatographed on a 40-g Redi-Sep column, eluting with 0-100% of a 90:10:1 mix of DCM/MeOH/NH4OH in DCM. The product isolated this way was impure, so the material was resubjected to chromatography on a 40-g Redi-Sep column, this time eluting with 0-100% EtOAc/Hexane. This gave (R)-2-(2-amino-2′-bromo-5H-spiro[oxazole-4,9′-xanthene]-7′-yloxy)benzonitrile as 94% pure by HPLC. It was a yellow solid after evaporation from DCM/hexane. Step 2: A vial was charged with (R)-2-(2-amino-2′-bromo-5H-spiro[oxazole-4,9′-xanthene]-7′-yloxy)benzonitrile (75 mg, 0.167 mmol), pyridin-3-ylboronic acid (51.4 mg, 0.418 mmol), tetrakis(triphenylphosphine)palladium(0) (9.67 mg, 8.37 μmol), THF (837 μL), and potassium carbonate (418 μL, 0.837 mmol) (as a 2.0 M aq. solution). The vial was sealed and heated to 100° C. in a shaker overnight. The mixture was diluted with EtOAc and the layers were separated. The aqueous layer was extracted with EtOAc (2×). The combined organic extracts were evaporated, and the residue was chromatographed on a 25-g SNAP column, eluting with 0-80% of a 90:10:1 mix of DCM/MeOH/NH4OH in DCM to give (S)-2-(2-amino-2′-(pyridin-3-yl)-5H-spiro[oxazole-4,9′-xanthene]-7′-yloxy)benzonitrile as a pale-yellow solid.

Provenance & Evidence