反应详情

Acetic acid (50 μL, 0.87 mmol) was added to a mixture of 5-Formyl-2,2-dimethyl-4H-[1,3]dioxino[4,5-c]pyridine-8-carboxylic acid methyl ester [J. Org. Chem. 1999, 64, 4537] (220 mg, 0.87 mmol) and 4-fluoroaniline (125 μL, 1.3 mmol) in dry methanol (4 mL) and stirred at room temperature for 15 min. and sodium cyanoborohydride (72 mg, 1.3 mmol) was added. This mixture was stirred at room temperature for 3 h followed by evaporation of 90% of the methanol volume under reduced pressure. The residue was extracted with dichloromethane (3×25 mL) and the combined organic layers were dried (anh. Na2SO4), filtered and concentrated under reduced pressure. The crude product was purified by silica gel (methanol/dichloromethane, 0 to 10% methanol) to give 0.290 g of methyl 5-((4-fluorophenylamino)methyl)-2,2-dimethyl-4H-[1,3]dioxino[4,5-c]pyridine-8-carboxylate (compound 21a) (96%) as a white solid MS-ESI m/z 347 [MI-1]+.

1. stirringThis mixture was stirred at room temperature for 3 h
2. customfollowed by evaporation of 90% of the methanol volume under reduced pressure
3. extractionThe residue was extracted with dichloromethane (3×25 mL)
4. dry with materialthe combined organic layers were dried (anh. Na2SO4)
5. filtrationfiltered
6. concentrationconcentrated under reduced pressure
7. customThe crude product was purified by silica gel (methanol/dichloromethane, 0 to 10% methanol)