反应详情

A solution of 3-bromo-2-methyl-7-(2,4,6-trimethyl-phenyl)-4,5,6,7-tetrahydro-2H-pyrazolo[3,4-b]pyridine (1-3; 0.040 g, 1.2 mmol) in 6 mL of dry THF was cooled to −78° C. in a dry ice-acetone bath under an argon atmosphere and treated with n-butyllithium in hexane (0.83 mL, 1.32 mmol). After 10 m a solution of 1 M zinc chloride in ether (3.59 mL, 3.59 mmol) was added. The cooling bath was removed and the reaction stirred at room temperature. After 10 m acetyl chloride (0.113 g, 1.44 mmol) and tetrakis(triphenylphosphine)palladium(0) (28 mg, 0.024 mmol) were added and the brown solution was stirred for 2 hrs. The mixture was poured into 25 mL of saturated ammonium chloride solution, extracted twice with 25 mL portions of ethyl acetate. The combined organic extracts were washed with brine, dried over magnesium sulfate, and evaporated to dryness. The residue was purified on flash chromatography on silica gel eluting with ethyl acetate/hexane (15:85) giving 23 mg (6% yield) of 1-[2-methyl-7-(2,4,6-trimethyl-phenyl)-4,5,6,7-tetrahydro-2H-pyrazolo[3,4-b]pyridine-3-yl]ethanone as a colorless oil: ms (M+H)+=298.

1. customThe cooling bath was removed
2. stirringthe brown solution was stirred for 2 hrs
3. extractionextracted twice with 25 mL portions of ethyl acetate
4. washThe combined organic extracts were washed with brine
5. dry with materialdried over magnesium sulfate
6. customevaporated to dryness
7. customThe residue was purified on flash chromatography on silica gel eluting with ethyl acetate/hexane (15:85)