1,4-Thioarialkylation and/or amination of E-3- [4-bromebenzoyl] acrylic acid and some studies with the products

ABSTRACT

Recently[1], it was reported that 3-[4-bromobenzoyl] acrylic acid has antibacterial activity towards Staphilococcus aureus, Escherichia coli and Kllebsiella, this was ascribed to the presence of the highly conjugated benzoylacrylic system, which may react with biologically essential-SH groups. This prompted us to investigate the behaviour of 3[4-bromobenzoyl] acrylic acid [1] towards compounds bearing the sulphhydryl group. Thus, when compound [1], was allowed to react with thiophenol and/or thioglycolic acid in dry benzene in the presence of few drops of piperidine is a catalyst[2], it afforded 2-phenyhmercapto-3-[4-bromobenzoyl] propionic acid, and 2-carboxymethyl mercapto-3-[4-bromobenzoyl] propionic acid [2 a and b], respectively. The structure of the acids 2 was proved from their infrared spectra, which show absorptions at 1674, 1683 cm[-1] [V[C=O] of ketone], 1700 and 1725 cm[-1] [V[c=o] of carboxylic acid] and broad basin peak centered at 3300 cm[-1]1 [V[OH] of acids] the electron impact fragmentation of compound 2a exhibits m/e =348[M[+]-18]. The [1]H-NMR spectrum of compound 2b in DMSO exhibits signals at 2.3 [S, 2H, S-CH[2]-COO], 3.1 [octet, 2H, C-CH[2]-] nonequivalent diasterotopic methylene protons, 4[quartet, -CH, methane proton], 7.7-7.9 [m, 4H, Ar-H], 12.79 [broad singlet, OH protons which disappear in D[2]O]