154902-51-9

24424-99-5

72120-71-9

154902-51-9

General procedure for the synthesis of (S)-3-(benzo[b]thiophen-3-yl)-2-((tert-butoxycarbonyl)amino)propionic acid from di-tert-butyl dicarbonate and (S)-2-amino-3-(benz[b]thiophen-3-yl)propionic acid: to a THF:H2O (1.0 g, 4.52 mmol) solution containing K2CO3 (0.75 g, 5.33 mmol) and (S)-2-amino-3-(benzo[b]thieno -3-yl)propionic acid (1.0 g, 4.52 mmol) to a solution of THF:H2O (1:1, v/v) was slowly added di-tert-butyl dicarbonate (1.09 g, 5 mmol). Subsequently, the reaction mixture was gradually warmed to room temperature and stirred continuously overnight. Upon completion of the reaction, the mixture was concentrated to remove most of the solvent and then the residue was dissolved in a mixture of EtOAc and H2O. The pH of the aqueous phase was adjusted to 1-2 with 6N HCl, followed by three extractions with EtOAc. The organic layers were combined, dried with anhydrous Na2SO4, filtered and concentrated to give 1.22 g of the target product as a white foamy solid in 84% yield.