Synthesis, antioxidant and antimicrobial activities of novel thiopyrano[2,3-d]thiazoles based on aroylacrylic acids

Here it is described the synthesis, antioxidant and antimicrobial activity determination of novel rel-( $$5R,6S,7R$$ )-6-benzoyl-7-phenyl-2-oxo-3,5,6,7-tetrahydro-2H-thiopyrano[2,3-d]thiazole-5-carboxylic acids. The target compounds were obtained in good yields from 5-arylidene-4-thioxo-2-thiazolidinones and $$\upbeta $$ -aroylacrylic acids via regio- and diastereoselective hetero-Diels–Alder reaction. The stereochemistry of the cycloaddition was confirmed by NMR spectra. The antioxidant and antimicrobial activity screening identified 7 compounds (3c, 3e, 3f, 3g, 3k, 3l, 3p) with a high level of free radical scavenging (43–77% DPPH assay), and compounds with significant influence on Staphylococcus aureus, Bacillus subtilis and Candida albicans (MIC 3.13–6.25 $$\upmu \hbox {g/mL}$$ ), but slight effect on Escherichia coli.