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

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 for the first time to give Z isomer compounds (4a-e). The compounds are new heterocycles and evaluated their microbial activity.