Iodine → 4-Allyl-3,5-bis-benzyloxy-benzoic acid tert-butyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a suspension of Mg pieces (5.76 g, 0.24 mol) in Et2O (250 mL) was added catalytic I2, followed by i-PrMgBr (19.7 g, 0.16 mol) in one portion. The mixture was irradiated with heating. After stirring for 2 hr, the resulting solution was added to THF (200 mL). n-BuLi (128 mL, 2.5 M in hexane, 0.32 mol) was added drop wise to the mixture 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 (2.9 g, 0.032 mol), LiCl (2.7 g, 0.064 mol) and allyl bromide (51.5 g, 0.43 mol) were added sequentially. After stirring for another 30 min at −78° C., TLC (EtOAc/petroleum oil=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 combined organic layers were washed with brine, dried over Na2SO4 and concentrated to give the title compound (35 g, 76.4% yield) as a yellow oil. 1H NMR (400 MHz, CDCl3): δ 7.57-7.25 (m, 12H), 5.98(m, 1H), 5.13 (s, 4H), 5.04-4.88 (m, 2H), 3.57 (m, 2H), 1.59 (s, 9H).

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