反应详情

To a solution of 3-chloro-2-isopropoxy-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine (Preparation 5, 297.6 g, 897.9 mmol) in acetic acid:water (2.2 L:1.0 L) at 0° C. was added peracetic acid (191 mL; 1.077 mol) and the reaction was allowed to warm gradually to room temperature. After 4 hours the reaction was complete and was quenched with 0.5 M aqueous solution of sodium thiosulfate (225 mL). The resulting dark solution was evaporated to dryness and the residue was passed through a plug of silica eluting with heptanes:ethyl acetate 1:0 to 10:1 to afford a pale yellow viscous oil which contained 8% of the 4-isomer. Further silica gel column chromatography was performed eluting with EtOAc:heptane 1:4 to afford a pale yellow solid which was triturated with heptanes and dried under suction to afford the title compound as a white solid (110 g, 65% over two steps).

1. customwas quenched with 0.5 M aqueous solution of sodium thiosulfate (225 mL)
2. customThe resulting dark solution was evaporated to dryness
3. customto afford a pale yellow viscous oil which
4. washFurther silica gel column chromatography was performed eluting with EtOAc:heptane 1:4
5. customto afford a pale yellow solid which
6. customwas triturated with heptanes
7. customdried under suction