Synthesis, photochemical E (trans)-->Z (cis) isomerization and antimicrobial activity of 2-chloro-5-methylpyridine-3-olefin derivatives.

Abstract 2-Chloro-5-methylpyridine-3-olefin derivatives ( 3a - e ) have been synthesized from 2-chloro-5-methylnicotinaldehyde ( 1 ) and studied their photochemical E ( trans ) →  Z ( cis ) isomerization upon direct irradiation and triplet sensitized excitation for the first time. The triplet sensitized excitations of the compounds yielded high Z ( 4a – e ) isomer composition, whereas the direct excitation results in less Z ( 4a – e ) isomer composition, indicating triplet pathway is very efficient in converting the E ( trans ) →  Z ( cis ) isomer. Thus synthesized E ( 3a – c and 3e ) and generated Z ( 4a – c and 4e ) isomers were tested for antimicrobial activity. Antifungal activity of these pyridine derivatives are closely comparable to the standard used.