Dibutyl sulfide → (+/-)-Ethyl 3-(4-ethylpyridin-2-yl)-4-(7-methyl-2-((2-(trimethylsilyl)ethoxy)methyl)-2H-indazol-5-yl)butanoate

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Reaction Conditions

Reaction Steps

To a 50-mL oven-dried flask was added di-n-butylsulfide (244 mg, 1.665 mmol, 4.4 equiv) and cuprous iodide (159 mg, 0.832 mmol, 2.2 equiv) under nitrogen. Anhydrous ether (1.2 mL) was added and the suspension was cooled to 0° C. before the solution of 2-pyridinyl lithium was added via canuula. A yellowish brown precipitate was formed. After stirring at 0° C. for 20 min, the cooling bath was removed and ethyl 4-(7-methyl-2-((2-(trimethylsilyl)ethoxy)methyl)-2H-indazol-5-yl)but-2-enoate (141.7 mg, 0.378 mmol, 1.0 equiv.) in anhydrous ether (1.2 mL) was added via syringe. The solution was stirred at room temperature for 1 h. The reaction mixture was then partitioned between an aqueous ammonium hydroxide/ammonium chloride solution and ethyl acetate (upon shaking, the solids gradually dissolved to a give blue aqueous solution). The layers were separated and the organic layer was washed with water, brine, dried over sodium sulfate and concentrated in vacuo. Flash column chromatography (5% methanol in methylene chloride) afforded the desired product (80 mg, 44%) which was carried on without farther purification. MS (ESI) 482 (MH)+.

Provenance & Evidence