Dibromomethane → HCID 19428661, compound

Participants

Reaction Steps

2 Dibromomethane (6.13 g) and zinc dust (6.92 g) were added to dry tetrahydrofuran (100 ml), and the resulting mixture was cooled to 0°~5° C. A dichloromethane solution (25.9 ml) of 1M titanium tetrachloride was added to the tetrahydrofuran solution in about 10 min, and the resulting mixture was allowed to react for 4 days at 0°~5° C. Then a solution of (RS)-4-tert-butyldimethylsilyloxy-3-methyl-2-(2-propenyl)cyclopent-2-ene-1-one (6.27 g) in dichloromethane (30 ml) was added at 0°5° C. in about 10 min. After the mixture was allowed to react for 12 hours at the same temperature, the reaction mixture was diluted with pentane (150 ml), and then a slurry consisting of sodium bicarbonate (150 g) and water (80 ml) was slowly added. After stirring for 2 hours at the same temperature, the reaction mixture was filtered by passing through a celite pad, and the separated layer was dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure. The resultant residue was subjected to silica gel column chromatography (eluent; n-hexane: ethyl acetate=50:1) to afford the desired product, (RS)-2-methyl-4-methylidene-3-(2-propenyl)-1-tert-butyldimethylsilyloxycyclopent-2-ene (5.5 g, yield 88.4%) as a pale yellow oil.

Provenance & Evidence