Ethyl formate → 3-Chloro-4-pyridinecarboxaldehyde

Temperature

-70 °C

THF (200 mL) is chilled to −70° C. in a dry flask under N2, and N-butyllithium (24.4 mL, 55.0 mmol) is added drop-wise. The reaction is placed in an ice bath and DIA (7.71 mL, 55.0 mmol) in THF (20 mL) is added drop-wise. The solution is again chilled to −70° C., and 3-chloropyridine (4.75 mL, 50.0 mmol) in THF (20 mL) is added drop-wise. The reaction is allowed to stir for 4 h at −70° C. and ethyl formate (4.44 mL, 55.0 mmol) in THF (20 mL) is added. The reaction is stirred for an additional 3 h at −70° C. and quenched with H2O (500 mL). The layers are allowed to separate, and the aqueous layer is extracted with EtOAc (3×250 mL). The combined organic layer is dried over MgSO4, filtered, and concentrated to a dark brown solid. The crude material is chromatographed over 250 g slurry-packed silica, eluting with 50% EtOAc/hexane to give 3-chloroisonicotinaldehyde (C120) as an off-white solid (55% yield). MS (EI) for C6H4ClNO, m/z: 141 (M)+.

1. customThe reaction is placed in an ice bath
2. stirringThe reaction is stirred for an additional 3 h at −70° C.
3. customquenched with H2O (500 mL)
4. customto separate
5. extractionthe aqueous layer is extracted with EtOAc (3×250 mL)
6. dry with materialThe combined organic layer is dried over MgSO4
7. filtrationfiltered
8. concentrationconcentrated to a dark brown solid
9. customThe crude material is chromatographed over 250 g slurry-packed silica
10. washeluting with 50% EtOAc/hexane

ORD record

ord-f8284e6a70a44958abb75762626c2842

Source dataset

uspto-grants-2005_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06911543B2