Chlorotrimethylsilane → HCID 57907576, compound

Temperature

-78 °C

To a stirred solution of 27.5 g (80.0 mmol) of tert-butyl 3-[4-(benzyloxy)-4-oxobutyl]-1H-pyrazole-1-carboxylate from step D in 250 mL of anhydrous THF at −78° C. under an atmosphere of nitrogen was added 88 mL (88 mmol) of a 1.0 M solution of sodium bis(trimethylsilyl)amide in anhydrous THF. The resulting dark yellow solution was stirred for 1 h at −78° C. and then 12 ml (96 mmol) of chlorotrimethylsilane was added dropwise over 5 min. The resulting mixture was stirred for 25 min during which time the reaction became a light yellow color. Next, 16 g (88 mmol) of solid N-bromosuccinimide was added in one portion and the resulting mixture was stirred for 3 hrs at −78° C. followed by gradual warming to 0° C. over 1 h. The reaction was quenched with a saturated aqueous ammonium chloride solution and the aqueous phase extracted with ethyl acetate (3×200 mL). The combined organics were washed with brine, dried over magnesium sulfate, filtered and evaporated to dryness in vacuo to afford the title compound as a yellow gum. The crude product appears to be a 1:1 mixture of starting material and desired product by NMR and was used without further purification in the next step. LC-MS: m/z (ES) 424 (MH)+.

1. stirringThe resulting mixture was stirred for 25 min during which time the reaction
2. stirringthe resulting mixture was stirred for 3 hrs at −78° C.
3. temperatureby gradual warming to 0° C. over 1 h
4. customThe reaction was quenched with a saturated aqueous ammonium chloride solution
5. extractionthe aqueous phase extracted with ethyl acetate (3×200 mL)
6. washThe combined organics were washed with brine
7. dry with materialdried over magnesium sulfate
8. filtrationfiltered
9. customevaporated to dryness in vacuo

ORD record

ord-b69e7c7e7ad54a748401065ef0331d84

Source dataset

uspto-grants-2013_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08501786B2