Lithium Hexamethyldisilazide → Gsk-5498A

Participants

Reaction Conditions

Reaction Steps

A solution of 2,6-difluoro-N-1H-pyrazol-3-ylbenzamide (for a preparation see Intermediate 9) (4.59 g, 20.6 mmol) in THF (45 ml) was cooled to 5° C. under nitrogen. A solution of 1.0 M lithium bis(trimethylsilyl)amide in THF (20.6 ml, 20.6 mmol) was added dropwise maintaining the temperature below 10° C. After 10 minutes a solution of 2-(bromomethyl)-1-fluoro-3-(trifluoromethyl)benzene (5.29 g, 20.6 mmol, JRD fluorochemicals Ltd) in THF (9 ml) was added and the reaction mixture was stirred at room temperature overnight. The reaction was quenched using 1 M hydrochloric acid (50 ml). The reaction mixture was extracted with ethyl acetate (2×50 ml). The combined organic extracts were washed with brine (50 ml), dried with magnesium sulphate, filtered and solvent removed in vacuo. The crude material was dissolved in DCM and applied to a 330 g silica cartridge. The cartridge was eluted with 0-100% ethyl acetate in cyclohexane over 45 min. The required fractions were combined and evaporated in vacuo, to give the title compound as a white solid (6.75 g). The white solid (6.75 g) was dissolved in ethyl acetate (70 ml) and heated to 50° C. Cyclohexane (280 ml) was then added dropwise over 20 min.

Provenance & Evidence