反应详情

Et2O (16.2 g, 99.5 mmol) was added to a solution of 5-bromo-2-hydroxybenzaldehyde (200 g, 995 mmol) in CH2Cl2 (500 mL), and then a solution of ethyl diazoacetate (180 g, 1.42 mol) in CH2Cl2 (500 mL) was introduced as evolution of N2 gas while the reaction was not allowed over 38° C. Once gas evolution ceased, the reaction mixture was concentrated by rotary evaporator and conc. H2SO4 (129 g, 1.29 mol, 98%) was added to the mixture while stirring. After 20 minutes, the acidic mixture was neutralized with Na2CO3 (a.q.). After the mixture was stored and crystallized overnight, ethyl 5-bromobenzofuran-3-carboxylate (100 g, yield: 75%) was obtained by filtration. 1H-NMR (400 MHz, CDCl3) δ 8.25 (s, 1H), 8.15˜8.21 (m, 1H), 7.44˜7.50 (m, 1H), 7.37˜7.42 (m, 1H), 4.41 (q, J=7.2 Hz, 2H), 1.43 (t, J=7.2 Hz, 3H).

1. customwas not allowed over 38° C
2. additionwas added to the mixture
3. customcrystallized overnight