Chlorotrimethylsilane → HCID 57907576, compound

Participants

Reaction Conditions

Reaction Steps

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)+.

Provenance & Evidence