18-Crown-6 → (E)-2-iodo-1-methyl-4-(2-(2,6,6-trimethylcyclohex-1-enyl)vinyl)benzene

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To a −78° C. solution of triphenyl((2,6,6-trimethylcyclohex-1-enyl)methyl)phosphonium bromide (24) (0.3787 g, 0.79 mmol) and 18-crown-6 (0.0246 g, 0.093 mmol) in CH2Cl2 (7 mL) was added potassium tert-butoxide (0.0991 g, 0.88 mmol). The mixture was sonicated at room temperature under argon for 2 min, resulting in a deep red solution. The mixture was cooled to −78° C. then a solution of 3-iodo-4-methylbenzaldehyde (0.1742 g, 0.71 mmol) in CH2Cl2 (3 mL+2 mL) was added and stirred for 5 min. The reaction mixture was allowed to warm to room temperature. Additional phosphonium salt 24 (0.3725 g, 1.6 mmol), 3-iodo-4-methylbenzaldehyde (0.2538 g, 1.7 mmol) and potassium tert-butoxide (0.1548 g, 1.38 mmol) were then added and the reaction was stirred at room temperature for 4.3 h. The reaction was partitioned between EtOAc and water then the combined organics were washed with brine, dried over MgSO4 and concentrated under reduced pressure. Purification by flash chromatography (6 to 50% EtOAc-hexanes gradient) gave (E)-2-iodo-1-methyl-4-(2-(2,6,6-trimethylcyclohex-1-enyl)vinyl)benzene as a white solid. Yield (0.26 g, 45%): NMR (400 MHz, DMSO-d6) δ 7.91 (d, J=1.6 Hz, 1H), 7.44 (dd, J=7.6, 1.2 Hz, 1H), 7.29 (d, J=7.2 Hz, 1H), 6.71 (d, J=16.4 Hz, 1H), 6.28 (6, J=16.8 Hz, 1H), 2.35 (s, 3H), 2.01 (t, J=6.4 Hz, 2H), 1.72 (s, 3H), 1.57-1.64 (m, 2H), 1.43-1.47 (m, 2H), 1.04 (s, 6H).

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