反应详情

温度

-60 °C

Cyclopropyltriphenylphosphonium bromide (10.8 g, 28 mmol) was suspended in dry THF (30 mL) and cooled to −60° C. N-Butyllithium (1.6M in THF, 17 mL, 27 mmol) was added dropwise at −40 to −60° C. The temperature was raised to 20° C. and after 3 hours at this temperature, the reaction mixture was cooled to −60° C. 1,4-Cyclohexane dione mono ethylene ketal (4.0 g, 26 mmol) dissolved in THF (30 mL) was added at −60° C. whereafter the temperature was raised to 20° C. After 16 hours the reaction mixture was diluted with THF (75 mL) filtered through hyflo and concentrated in vacuo. The residue was purified by flash chromatography (4×15 cm column of silica) using heptane and ethyl acetate (4:1) as eluent to give 2.5 g of 8-cyclopropylidene-1,4-dioxa-spiro[4.5]decane (cf Synthetic Communications 21(20), 2015-2023, 1991).

1. temperatureThe temperature was raised to 20° C. and after 3 hours at this temperature
2. temperaturethe reaction mixture was cooled to −60° C
3. additionwas added at −60° C. whereafter the temperature
4. temperaturewas raised to 20° C
5. filtrationfiltered through hyflo
6. concentrationconcentrated in vacuo
7. customThe residue was purified by flash chromatography (4×15 cm column of silica)