Environmentally benign synthesis and anti-mycobacterial evaluation of 9,10-dihydro-4-methyl-chromeno[8,7-e][1,3]oxazin-2(8H)-one derivatives

In the present study, a series of 9,10-dihydro-4-methyl-chromeno[8,7-e][1,3]oxazin-2(8H)-one derivatives (4a-j) have been synthesized by using one-pot Mannich type condensation cyclization reaction of 7-hydroxy-4-methylcoumarin, formaldehyde and primary amines in water at 80-90 degrees C. These products have been characterized using various spectroscopic techniques (H-1 and C-13 NMR, IR, and MS) followed by evaluation of their' in-vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv. The compounds 4g and 4h display the lowest MIC of 5 ug/mL and offer a remarkable viability of HEK-293 cells at the highest test concentration (100 mu g/mL) in toxicity assay.