5-Amino-6-bromo-3,4-dihydro-2H-1-benzopyran-8-carboxylicacid synthesis

Yield:941692-27-9 100%

Reaction Conditions:

Stage #1: methyl 5-(acetylamino)-6-bromo-3,4-dihydro-2H-chromene-8-carboxylatewith sodium hydroxide in water; for 16 h;Heating / reflux;
Stage #2: with hydrogenchloride in water at 20; pH=4;

Steps:

15

A stirred suspension of methyl 5-(acetylamino)-6-bromo-3,4-dihydro-2H- chromene-8-carboxylate (may be prepared as described in Description 14)(9.2g, 28mmol) in 10% sodium hydroxide solution (200ml) was heated under reflux for 16h. The solution was then cooled to ambient temperature and brought to pH4 by the addition of concentrated hydrochloric acid, whereupon precipitation of a white solid occurred. The solid was filtered, washed with water, dried at 5O⁰C and identified as the title compound (D15) (7.7g, 28mmol,100%) δH (DMSO-d6, 400MHz) 1.91-1.97 (2H, m), 2.46 (2H, t, J = 5.2Hz), 4.11 (2H, t, J = 5.2Hz), 5.69 (2H, br, s), 7.66 (1 H, s), 11.8 (1 H, br, s).Mass Spectrum: Ci₀H₁₀BrNO₃ requires 271/273; found 272/274 (MH⁺).

References:

WO2007/68739,2007,A1 Location in patent:Page/Page column 27