1H-Pyrazole-5-carboxylic acid, 3-[(1,1-dimethylethyl)dimethylsilyl]-, ethyl ester synthesis

Yield:1571073-90-9 2.1 g

Reaction Conditions:

at 70; for 20 h;Sealed tube;

Steps:

5.i (i) Ethyl 3-(tert-butyldimethylsilyl)-1 H-pyrazole-5-carboxylate

Ethyl 2-diazoacetate (85 wt %) (1.740 mL, 14.26 mmol) and tert-butyl(ethynyl)dimethylsilane (2.66 mL, 14.26 mmol) were combined and warmed to 70°C in a sealed tube behind a blast screen for 20 h. After this time the reaction was diluted with isohexanes (10 mL) and the solid collected by filtration, dried under vacuum to afford thesub-title compound (2.1 g) as a white powder.IH NMR (400 MHz; CDCI3) 6 10.69 (br.s, IH), 6.99 (s, IH), 4.41 (q, 2H), 1.41 (t, 3H), 0.92 (s, 9H), 0.32 (s, 6H). LCMS m/z 255 (M÷H) (ESj; 253 (M-H) (ES-)

References:

WO2014/33449,2014,A1 Location in patent:Page/Page column 48; 49