Toluene → 6-Bromo-4,4-dimethyl-2-methylene chroman

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Reaction Steps

A stirred, cooled (ice bath) solution of 6-bromo-4,4-dimethyl-chroman-2-one available in accordance with U.S. Pat. No. 5,399,561 incorporated herein by reference (1 g, 3.92 mmol) in 8 mL of anhydrous tetrahydrofuiran was treated with a 0.5 M solution of μ-chloro-μ-methylene-[ bis(cyclopentadienyl)titanium]dimethylaluminum (Tebbe reagent) in toluene (8.23 mL, 4.12 mmol). After 10 minutes, the reaction mixture was poured into ice-water mixture containing 50 mL of 1M sodium hydroxide and extracted with hexane. The hexane extract was washed with brine (×1), filtered over a bed of celite and evaporated in vacuo to an oil which was subjected to flash column chromatography over silica gel (230-400 mesh) using hexane as the eluent to afford the title compound (0.74 g, 74%) as a clear oil. 1H NMR (300 MHz, CDCl3): δ 7.34 (d, 1H, J=2.3 Hz), 7.23 (dd, 1H, J=2.3, 8.5 Hz), 6.77 (d, 1H, J=8.0 Hz), 4.61 (d, 1H, J=0.73 Hz), 4.17 (d, 1H, J=0.73 Hz), 2.33 (s, 2H), 1.27 (s, 6H).

Provenance & Evidence