A highly atom economic, chemo-, regio- and stereoselective synthesis, and discovery of spiro-pyrido-pyrrolizines and pyrrolidines as antimycobacterial agents

The 1,3-dipolar cycloaddition of azomethine ylides derived from acenaphthenequinone and α-amino acids viz. proline, phenylglycine and sarcosine to a series of 1-methyl-3,5-bis[(E)-arylmethylidene]tetrahydro-4(1H)-pyridinones afforded novel spiro-pyrido-pyrrolizines and pyrrolidines chemo-, regio- and stereoselectively in quantitative yields. These compounds were screened for their in vitro activity against Mycobacterium tuberculosis H37Rv (MTB), multi-drug resistant Mycobacterium tuberculosis (MDR-TB) and Mycobacterium smegmatis using agar dilution method. Among the synthesized compounds, spiro-[2.2″]acenaphthene-1″-one-spiro[3.3′]-5′-(2-chlorophenylmethylidene)-1′-methyltetrahydro-4′(1H)-pyridinone-4-(2-chlorophenyl)hexahydro-1H-pyrrolizine (3e) was found to be the most active with a minimum inhibitory concentration (MIC) of 0.4 μg/mL against MTB and MDR-TB.