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温度

0 °C

To a suspension of tetraethoxytitanium (3.40 g, 14.93 mmol) in THF (16.58 ml) was added 3-bromo-7-iodo-5H-chromeno[2,3-b]pyridin-5-one (2.00 g, 4.98 mmol). The suspension was cooled to 0° C. and (2-ethoxy-2-oxoethyl)zinc(II) bromide (149 ml, 14.93 mmol) was added drop wise. The reaction mixture was allowed to warm to RT and stirred 1 h. The reaction mixture was quenched with aqueous, half-saturated NaHCO3 solution (20 mL) and stirred for 30 min. The solution was filtered through a pad of celite and the filter cake was rinsed with EtOAc. The organic layer was separated and concentrated under reduced pressure to afford ethyl 2-(3-bromo-5-hydroxy-7-iodo-5H-chromeno[2,3-b]pyridin-5-yl)acetate as a yellowish solid.

1. temperatureto warm to RT
2. customThe reaction mixture was quenched with aqueous, half-saturated NaHCO3 solution (20 mL)
3. stirringstirred for 30 min
4. filtrationThe solution was filtered through a pad of celite
5. washthe filter cake was rinsed with EtOAc
6. customThe organic layer was separated
7. concentrationconcentrated under reduced pressure