Acetonitrile → (S)-7-bromo-3-(difluoromethoxy)-2',6'-dihydrospiro[chromeno[2,3-c]pyridine-5,3'-[1,4]oxazin]-5'-amine

Participants

Reaction Steps

(S)-7-bromo-3-methoxy-2′,6′-dihydrospiro[chromeno[2,3-c]pyridine-5,3′-[1,4]oxazin]-5′-amine (0.611 g, 1.624 mmol) was dissolved in HOAc (6.14 mL, 107 mmol). Hydrobromic acid (48% aq.; 6.06 mL, 53.6 mmol) was added and the reaction was stirred at 100° C. for two hours. The reaction was diluted with water, slowly neutralized to pH 7 with 6N NaOH, and stirred overnight, during which a light pink solid crashed out of solution. The solution was filtered, and the solid was air dried to afford (S)-5′-amino-7-bromo-2′,6′-dihydrospiro[chromeno[2,3-c]pyridine-5,3′-[1,4]oxazin]-3-ol (0.554 g, 1.530 mmol, 94% yield) as an off-white solid. [M+H]+=363.9 Step 2: A flask was charged with (S)-5′-amino-7-bromo-2′,6′-dihydrospiro[chromeno[2,3-c]pyridine-5,3′-[1,4]oxazin]-3-ol (0.250 g, 0.690 mmol), cesium fluoride (9.17 mg, 0.069 mmol), and acetonitrile (6.90 mL). Trimethylsilyl 2,2-difluoro-2-(fluorosulfonyl)acetate (0.272 mL, 1.381 mmol) was added slowly and the reaction was stirred for 15 minutes. The reaction was diluted with EtOAc and washed with water. The aqueous layer was extracted with EtOAc, and the combined organic layers were washed with brine, dried with sodium sulfate, filtered, and concentrated. The material was purified via column chromatography (0-10% MeOH/DCM), to afford (S)-7-bromo-3-(difluoromethoxy)-2′,6′-dihydrospiro[chromeno[2,3-c]pyridine-5,3′-[1,4]oxazin]-5′-amine (0.056 g, 0.136 mmol, 19.68% yield) as a light yellow solid. [M+H]+=411.9 Step 3: A microwave vial was charged with (S)-7-bromo-3-(difluoromethoxy)-2′,6′-dihydrospiro[chromeno[2,3-c]pyridine-5,3′-[1,4]oxazin]-5′-amine (0.056 g, 0.136 mmol). 2-fluoropyridin-3-ylboronic acid (0.038 g, 0.272 mmol), potassium phosphate (0.087 g, 0.408 mmol), and bis(di-tert-butyl(4-dimethylaminophenyl)phosphine)dichloropalladium(II) (4.81 mg, 6.79 μmol) were added. The vial was flushed with Ar (g), then dioxane (0.509 mL) and water (0.170 mL) were added in sequence. The vial was sealed and heated in a Biotage Initiator microwave reactor for 30 min at 100° C. The reaction was diluted with EtOAc and washed with water. The aqueous layer was extracted with EtOAc, and the combined organic layers were washed with brine, dried with sodium sulfate, filtered, and concentrated. The material was purified via column chromatography (0-10% MeOH/DCM) to afford (S)-3-(difluoromethoxy)-7-(2-fluoropyridin-3-yl)-2′,6′-dihydrospiro[chromeno[2,3-c]pyridine-5,3′-[1,4]oxazin]-5′-amine (0.042 g, 0.098 mmol) as a light yellow solid. [M+H]+=429.0

Provenance & Evidence