(4-Chloro-3-ethoxyphenyl)methanol → 4-Chloro-3-ethoxybenzaldehyde

To a solution of 4-chloro-3-hydroxy-benzoic acid (3.0 g, 17.4 mmol, 1.0 equiv; commercially available) in DMF (15 mL) was added K2CO3 (4.81 g, 34.8 mmol, 2.0 equiv) and ethyl iodide (4.03 mL, 5.97 g, 38.2 mmol, 2.2 equiv). The reaction mixture was stirred for 6 h at rt, diluted with water (20 mL) and extracted with ethyl acetate (3×50 mL). The organic phases were dried over Na2SO4 and concentrated to afford 3.6 g (91%) of 4-chloro-3-ethoxy-benzoic acid ethyl ester. The crude ester was then dissolved in THF (20 mL) and cooled to −78° C. under Ar. A solution of diisobutylaluminium hydride (95 mL, 95.0 mmol, 6.0 equiv; 1 M solution in THF) was slowly added over a time period of 15 min, the cooling bath removed on completion of addition and the reaction allowed to reach 0° C. After 1 h the reaction was cooled to −78° C. and the excess hydride quenched by cautious addition of a solution of 1 M HCl (10 mL). The mixture was brought to rt, the organic phase separated and the aqueous layer extracted with ethyl acetate (3×100 mL). The combined organic phases were dried over Na2SO4 and concentrated by evaporation under reduced pressure providing 2.94 g (100%) of 4-chloro-3-ethoxy-benzyl alcohol. The crude alcohol (2.94 g, 15.75 mmol, 1.0 equiv) was dissolved in dichloromethane (15 mL) and activated MnO2 (5.48 g, 63.0 mmol, 4.0 equiv) was added. The reaction mixture was stirred for 16 h, after which time the reaction was filtered through Hyflo Super Cel and concentrated. The residue was purified by flash column chromatography on silica eluting with heptane/ethyl acetate (4:1) to yield 1.51 g (52%) of the title compound. 1H NMR (300 MHz, CDCl3): δ 1.51 (t, J=7.1 Hz, 3H), 4.19 (q, J=7.1 Hz, 2H), 7.37-7.42 (m, 2H), 7.55 (d, J=9.0 Hz, 1H), 9.94 (s, 1H).

1. filtrationafter which time the reaction was filtered through Hyflo Super Cel
2. concentrationconcentrated
3. customThe residue was purified by flash column chromatography on silica eluting with heptane/ethyl acetate (4:1)

ORD record

ord-5b1edde4319e458883313d096e133d65

Source dataset

uspto-grants-2010_12

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07855194B2