1012341-48-8

149709-59-1

1012341-48-8

The general procedure for the synthesis of (R,E)-5-([1,1'-biphenyl]-4-yl)-4-((tert-butoxycarbonyl)amino)-2-methyl-2-pentenoic acid from ethyl (4R)-5-([1,1'-biphenyl]-4-yl)-4-((tert-butoxycarbonyl)amino)-2-methyl-2-pentenoic acid was as follows: Step 1: 800 g of 95% ethanol and 400 g of pure water were mixed, compound I (1.3 mol) and lithium hydroxide (0.1833 mol) were added, and the reaction was held at reflux for 1 hour at 80 °C. After completion of the reaction, it was cooled to room temperature, activated carbon was added, heated to 42 °C and then continued to raise the temperature to 80 °C reflux. Incubate at room temperature for 2 hours. Step 2: The reaction mixture was thermally filtered and aqueous citric acid was added to the filtrate to terminate the reaction. Subsequently, the mixture was heated at reflux at 80°C for 1 hour and cooled to room temperature to crystallize. The crystals were collected by filtration and dried to give 55.4 g of dry Compound II in 79.05% molar yield and 99.20% purity.