Magnesium → Trans-3-[2-Benzyloxy-4-(1,1-dimethylheptyl)phenyl]-4-(2-propenyl)cyclohexanone

Participants

Reaction Conditions

Reaction Steps

A solution of 73.0 g. (0.188 mole) of 1-bromo-2-benzyloxy-4-(1,1-dimethylheptyl)benzene (BrZ') in 350 ml. of tetrahydrofuran was slowly added to 9.0 g. (0.375 mole) of 70-80 mesh magnesium metal. After a 5 minute initiation period the rate of addition was adjusted so as to just maintain reflux. The reaction was stirred 1.5 hours longer following completion of addition while cooling to 25° C. The reaction was cooled to -20° C. and 1.78 g. (9.38 mmoles) of cuprous iodide added. The resultant mixture was stirred 5 minutes and then a solution of 25.5 g. (0.188 mole) of 4-(2-propenyl)-2-cyclohexen-1-one (enone) in 30 ml. of tetrahydrofuran added dropwise while the reaction temperature was maintained at about -18° C. Additional 1.78 g. (9.38 mmoles) portions of cuprous iodide were added following addition of 1/3 and 2/3 of the enone reactant. The reaction was stirred 5 minutes longer at -20° C. and then added to 1000 ml. of ice cold saturated ammonium chloride. The quenched mixture was extracted with 1000 ml. of ether and the organic extract washed twice with 500 ml. of saturated ammonium chloride, once with 500 ml. of saturated sodium chloride, dried over magnesium sulfate and evaporated (aspirator) to an oil. The crude oil was purified via column chromatography on 1 kg. of silica gel eluted with 20% etherhexane to yield 58.3 g. (70%) of the title compound as an oil.

Provenance & Evidence