Toluene → 5-Bromo-3,3-dimethyl-7-isopropyl-2,3-dihydro-benzofuran

Participants

Reaction Conditions

Reaction Steps

A solution of 5-bromo-3,3,7-trimethyl-2,3-dihydro-benzofuran (Compound 7, 0.6 g, 2.5 mmol), benzophenone imine (0.54 g, 3 mmol), sodium-tert-butoxide (0.34 g, 3.5 mmol), tris(dibenzylideneacetone)dipalladium(0) (0.014 g, 0.01 5 mmol) and (S)-(-)-2,2'-bis(diphenylphosphino)-1,1'-binaphthyl (0.029 g, 0.047 mmol) in 10mL of anhydrous toluene was sparged with argon and heated at 80° C. for overnight. The reaction mixture was cooled to ambient temperature, diluted with diethyl ether and filtered. The filtrate was evaporated in vacuo and the residue was dissolved in 7 mL of tetrahydrofiran and treated with 1 mL of 2M hydrochloric acid, and stirred at ambient temperature for 0.5 hour. The volatiles were removed by distillation in vacuo and the residue was dissolved in 0.5M hydrochloric acid and washed with 1:1 hexanes: ethyl acetate. The aqueous phase was neutralized with saturated sodium bicarbonate solution and extracted with dichloromethane. The combined organic extracts were dried over anhydrous sodium sulfate, filtered and evaporated to afford the title compound as a dark brown oil (0.16 g, 36%). 1H-NMR (300 MHz, CDCl3): δ 6.33 (s, 2H), 4.18(s, 2H), 2.16(s, 3H), 1.30(s, 3H).

Provenance & Evidence