Iodine → 3,5-Bis-benzyloxy-4-(2-methyl-allyl)-benzoic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To a suspension of Mg pieces (7.9 g, 0.23 mol) in THF (250 mL) was added a catalytic amount of I2, followed by addition of i-PrMgBr (15 mL, 0.16 mol) drop wise. The mixture was heated slowly until refluxed violently. After stirring for 2 hr, the resulting mixture was added to THF (200 mL) and cooled to 0° C. n-BuLi (128 mL, 2.5 M in hexane, 0.32 mol) was added drop wise at 0° C. The mixture was cooled to −78° C. and 3,5-bis-benzyloxy-4-bromo-benzoic acid tert-butyl ester (200c) (50 g, 0.107 mol) was added drop wise. After the mixture was stirred for 1 hr, CuCN (2.85 g, 0.032 mol), LiCl (2.7 g, 0.064 mol), and 3-bromo-2-methyl-propene (43 mL, 0.43 mol) were added sequentially. After stirring for another 30 min at −78° C., TLC (EtOAc/petroleum ether=1/10) showed the reaction was complete. The mixture was quenched with saturated aqueous NH4Cl (150 mL). The aqueous layer was extracted with EtOAc (2×100 mL). The organic layer was washed with brine, dried over Na2SO4 and concentrated to give the title compound as a yellow oil (40 g, 84.4% yield).

Provenance & Evidence