Liu, Renyong published the artcileImproved synthetic method of captopril, Recommanded Product: 3-Bromo-2-methylpropanoic acid, the publication is Shenyang Yaoke Daxue Xuebao (1997), 14(4), 262-264, database is CAplus.
An improved synthetic method for captopril using methacrylic acid as the starting material was described. Treatment of methacrylic acid with hydrogen bromide gave 3-bromo-2-methylpropanoic acid which underwent chlorination with thionyl chloride, condensation with L-proline gave N-(R,S-3-bromo-2-methylpropanoyl)-L-prolin (I). I was resolved into optically pure stereo-isomer, which was treated with sodium trithiocarbonate to give captopril.
Shenyang Yaoke Daxue Xuebao published new progress about 56970-78-6. 56970-78-6 belongs to bromides-buliding-blocks, auxiliary class Bromide,Carboxylic acid,Aliphatic hydrocarbon chain,Inhibitor, name is 3-Bromo-2-methylpropanoic acid, and the molecular formula is C4H7BrO2, Recommanded Product: 3-Bromo-2-methylpropanoic acid.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary