An atom efficient, solvent-free, green synthesis and antimycobacterial evaluation of 2-amino-6-methyl-4-aryl-8-[(E)-arylmethylidene]-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]pyridine-3-carbonitriles

An atom efficient, green protocol for the synthesis of fifteen 2-amino-6-methyl-4-aryl-8-[(E)-arylmethylidene]-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]pyridine-3-carbonitriles in quantitative yields from the reaction of 1-methyl-3,5-bis[(E)-arylmethylidene]-tetrahydro-4(1H)-pyridinones with malononitrile in presence of solid sodium ethoxide under solvent-free condition is described. The compounds were tested for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant tuberculosis (MDR-TB), and Mycobacterium smegmatis using agar dilution method. 2-Amino-4-[4-(dimethylamino)phenyl]-8-(E)-[4-(dimethylamino)phenyl]methylidene-6-methyl-5,6,7,8-tetrahydro-4H-pyrano[3,2-c]-pyridine-3-carbonitrile was found to be the most potent compound (MIC: 0.43 μM) against MTB and MDR-TB, being 100 times more active than standard, isoniazid against MDR-TB.