Regioselective synthetic approaches towards 1,2,8,9-tetraazadispiro[4.1.4.2]trideca-2,9-dien-6-ones of potential antimicrobial properties

Reaction of 2,5-bis(arylmethylidene)cyclopentanones 1a–d with nitrilimines (generated in situ via triethylamine dehydrohalogenation of the corresponding hydrazonoyl chlorides 2a,b) in 1:2 molar ratio proceeds in a high regioselective manner affording monocycloadducts 3 and dicycloadducts in the form of two isomers 4, 5. Single crystal X-ray diffraction studies of the isolated crystalline form of 3c support the established structure and indicate that the formed product is 7E, 4S, 5R. Antimicrobial activity screening of the synthesized compounds 3–5, utilizing a variety of Gram-positive (Staphylococcus aureus, Enterococcus fecalis and Streptococcus agalactiae), Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae and Proteus vulgaris) and yeast (Candida albicans), exhibited that all the prepared analogues acquire promising activities against both Gram-positive and Gram-negative bacteria especially compounds 3b, 4a (antimicrobial active agents against Gram-positive bacteria) and 3c (antimicrobial active agent against Gram-negative bacteria).

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