B. Gangadasu

Facile and Selective Synthesis of Chloromethylpyridines and Chloropyridines Using Diphosgene/Triphosgene

Abstract Diphosgene and triphosgene in the presence of amines were found to be an excellent chlorinating agents with high selectivity for the preparation of chloromethylpyridines and chloropyridines from picoline‐N‐oxides and pyridine‐N‐oxides respectively. #IICT Communication No: 030808.

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 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.

ZrCl4 catalysed solvent free synthesis of coumarins

ZrCl4 is an efficient catalyst in the Pechmann condensation of phenols with ethyl acetoacetate and propynoic acid under solvent free conditions leading to formation of coumarins in very good yields.