反应详情

Zinc was activated according to a published procedure (Synthesis 1971; 415). Hydrated copper sulfate (14 g) was dissolved in water (150 mL) and added to zinc dust (60 g). The mixture was stirred for 2 hours under nitrogen. The activated zinc was isolated by filtration, washed with acetone and dried in a vacuum oven at 100° C. prior to use. The solution of 4-methylenetetrahydro-2H-pyran from Step A was dried with sodium sulfate and magnesium sulfate and filtered through Celite® (washing the cake with ether). This removed some orange solids which had precipitated. A solution of trichloroacetyl chloride (5.00 g; 27.5 mmol) in dry ether (250 mL) was added slowly (over 4 hours) to a stirred refluxing mixture of the 4-methylenetetrahydro-2H-pyran in dry ether (250 mL) and the activated zinc (5.00 g; 76.5 mmol) under nitrogen. The mixture was stirred for 16 hours at reflux. The solution was filtered through Celite® and concentrated under reduced pressure. The material was purified by chromatography on silica gel, eluting with 10:1 hexane/ethyl acetate to give impure product (160 mg) as a colorless oil which was continued directly on to the next step.

1. washwashed with acetone
2. customdried in a vacuum oven at 100° C.
3. dry with materialThe solution of 4-methylenetetrahydro-2H-pyran from Step A was dried with sodium sulfate and magnesium sulfate
4. filtrationfiltered through Celite® (
5. washwashing the cake with ether)
6. customThis removed some orange solids which
7. customhad precipitated
8. temperaturerefluxing
9. temperatureat reflux
10. filtrationThe solution was filtered through Celite®
11. concentrationconcentrated under reduced pressure
12. customThe material was purified by chromatography on silica gel
13. washeluting with 10:1 hexane/ethyl acetate