Iodine → (E)-2-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethylnaphthalen-2-yl)-1-iodopropene

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Reaction Steps

A 2M solution of Me3Al and hexanes (6.80 mL, 13.6 mmol) was added to a solution of zirconocene dichloride (1.98 g, 6.80 mmol) and 18 mL of 1,2-dichloroethane at room temperature under argon. The resulting yellow-green solution was treated with a solution of (5,6,7,8-tetrahydro-3,5,5,8,8 -pentamethylnaphthalen-2-yl)acetylene (Compound 10, 1.53 g, 6.80 mmol) and 3 mL of 1,2-dichloroethane and the mixture stirred for 19 hours at room temperature. A solution of iodine (2.07 g, 8.13 mmol) and THF (15 mL) was added to the first solution and the reaction stirred at room temperature for 10 min. 5% aqueous Na2S2O3 was added carefully and the organic material was extracted with ethyl ether, washed with brine, dried (MgSO4) and concentrated in vacuo. The residue was purified by flash chromatography on silica gel (hexanes) to give the title compound (1.23 g, 49%) as a mixture that contained 0.59 g of 2-(5,6,7,8-tetrahydro-3,5,5,8,8-pentamethylnaphthalen-2-yl)propene. This biproduct is inert to the next palladium coupling reaction and so the mixture can be used without further purification.

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