Dimethylformamide → 5-Fluoro-1,3-benzothiazole-2-carbaldehyde

Temperatur

-50 °C

To a stirred solution of 36 g of 5-fluorobenzothiazole in 100 ml of diethyl ether cooled to -70° C. was added dropwise over a 5 minute period 9.4 ml of a 2.5M solution of n-butyl lithium in hexane. The reaction mixture was allowed to warm to -50° C. for one hour and was then cooled to -78° C. Dry dimethylformamide (2.8 ml) was added dropwise and the reaction mixture allowed to warm to room temperature over a period of two hours. The reaction was diluted with 300 ml of diethyl ether and washed with 1N hydrochloric acid (1×40 ml), water (1×40 ml), a saturated sodium bicarbonate solution (1×40 ml) and dried over magnesium sulfate. The solvent was removed and the residual product flash chromatographed on silica (50% ethyl acetate--hexane; v:v) to give 24.7 g of the titled product, m.p. 105°-107° C.

1. temperaturewas then cooled to -78° C
2. temperatureto warm to room temperature over a period of two hours
3. washwashed with 1N hydrochloric acid (1×40 ml), water (1×40 ml)
4. dry with materiala saturated sodium bicarbonate solution (1×40 ml) and dried over magnesium sulfate
5. customThe solvent was removed
6. customthe residual product flash chromatographed on silica (50% ethyl acetate--hexane; v:v)

ORD-Eintrag

ord-3e850f0d73d644b18e9a1342a678da7a

Quelldatensatz

uspto-grants-1994_06

DOI

10.6084/m9.figshare.5104873.v1

Patentnummer

US05322847