Iodine → 2Iodo-3,6-dimethoxy-2',4',6'-trimethylbiphenyl

Participants

Reaction Conditions

Reaction Steps

To an oven-dried 500-mL round bottom flask equipped with a magnetic stir bar was added 2-fluoro-1,4-dimethoxybenzene (6 g, 38.4 mmol, 1 equiv). The flask was purged with N2, and anhydrous degassed tetrahydrofuran (250 mL) was added. The solution was cooled to −78° C., and n-butyllithium (15.4 mL, 38.4 mmol, 1 equiv, 2.5 M in hexanes) was added dropwise over 12 minutes The mixture was stirred for another 30 minutes, and mesitylmagnesium bromide (38.4 mL, 38.4 mmol, 1 equiv, 1 M in tetrahydrofuran) was slowly added over 16 minutes. The reaction mixture was stirred at −78° C. for an additional hour, then removed from the cold bath to warm to room temperature. After 2 hours at room temperature, the reaction mixture was cooled in an ice bath to 0° C. and added a fresh solution of iodine (46.1 mL, 46.1 mmol, 1.2 equiv, 1 M in tetrahydrofuran) was added dropwise over 10 minutes. The flask was removed from the ice bath and stirred for an additional hour. Then the reaction mixture was concentrated to afford a red oil. The oil was dissolved in dichloromethane (100 mL), washed with aqueous saturated sodium thiosulfate (2×50 mL) and brine (50 mL), dried over sodium sulfate, filtered, and concentrated to furnish a brown-yellowish oil. Purification of the crude product by column chromatography (330-g column; gradient: 1.5 column volumes heptane, ramp up to 89:11 heptane:ethyl acetate over 8 column volumes, hold at 89:11 for 2 column volumes) followed by crystallization in heptane (20 mL) and a minimal amount of methyl tert-butyl ether, filtration, washing with cold heptane, and drying under vacuum afforded the title compound (6.64 g, >99 area % by HPLC, 45% yield). 1H NMR (400 MHz, CDCl3) δ ppm 6.99-6.96 (m, 2H), 6.94 (d, J=8.9 Hz, 1H), 6.82 (d, J=8.9 Hz, 1H), 3.90 (s, 3H), 3.69 (s, 3H), 2.37 (s, 3H), 1.93 (s, 6H). 13C NMR (100 MHz, CDCl3) δ ppm 152.4, 150.9, 137.6, 136.7, 135.8, 135.3, 127.7, 110.9, 109.3, 94.5, 56.9, 56.4, 21.6, 20.1.

Provenance & Evidence