Synthesis of novel triazolyl pyranochromen-2(1H)-ones and their antibacterial activity evaluation

A series of thirty-three novel triazolyl pyranochromen-2(1H)-one derivatives have been synthesized via Cu (I) catalysed Huisgen 1,3-dipolar cycloaddition reaction. All of the synthesized compounds have been fully characterized from their spectral data and evaluated for antibacterial activity against both gram-positive and gram-negative bacteria. The activity results revealed that amongst all the compounds screened, six compounds, i.e. 2-[4-(((7-ethyl-2,2,6-trimethyl-8-oxo-2,3,4,8-tetrahydropyrano[3,2-g]chromen-10-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl]acetic acid (41), 10-[(1-(1,3-dihydroxypropan-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-3-ethyl-4,8,8-trimethyl-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (44), 3-ethyl-4,8,8-trimethyl-10-[(1-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (46), 2-[4-(((7-hexyl-2,2,6-trimethyl-8-oxo-2,3,4,8-tetrahydropyrano[3,2-g]chromen-10-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl]acetic acid (52), 10-[(1-(1,3-dihydroxypropan-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-3-hexyl-4,8,8-trimethyl-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (55) and 3-hexyl-4,8,8-trimethyl-10-[(1-((2R,3R,4S,5S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2H-pyran-2-yl)-1H-1,2,3-triazol-4-yl)methoxy]-7,8-dihydropyrano[3,2-g]chromen-2(6H)-one (57), exhibited moderate activity against all the strains studied with zone of inhibition between 10 and 16 mm and MIC values in the range of 75–170 µg/mL as compared to the standard used. The information obtained from structure–activity relationship can be used to design and develop the next generation of compounds with higher antibacterial efficacy.