反应详情

Ethyl 7-(4-(tert-butoxycarbonyl)phenoxy)-6-chlorochroman-4-carboxylate (221 g, 0.511 mol) was dissolved in hydrogen chloride in ethyl acetate (2.4 N, 1.6 L, 3.84 mol) and the resulting solution was stirred at ambient temperature for 16 hours. The solution was concentrated to give 198 g of crude 4-(6-chloro-4-(ethoxycarbonyl)chroman-7-yloxy)-benzoic acid. The crude product was recrystallized by dissolving in hot isopropyl acetate (0.5 L) and diluting with hexanes (1.1 L). After 48 hours, the crystals were collected and wash with hexanes. The resulting white solids were dried under high vacuum to give 4-(6-chloro-4-(ethoxycarbonyl)chroman-7-yloxy)benzoic acid (169 g, 88% yield). 1H NMR (400 MHz, CDCl3) δ 8.08 (d, J=8.9 Hz, 2H), 7.38 (s, 1H), 6.98 (d, J=8.8 Hz, 2H), 6.60 (s, 1H), 4.21-4.31 (m, 4H), 3.75 (t, J=5.4 Hz, 1H), 2.31-2.37 (m, 1H), 2.08-2.15 (m, 1H), 1.32 (t, J=7.0 Hz, 3H).

1. concentrationThe solution was concentrated