Synthesis of some new 2-(substituted-phenyl)imidazo[4,5-c] and [4,5-b]pyridine derivatives and their antimicrobial activities.

The synthesis of 5H-imidazo[4,5-c]pyridines analogues (1a - 1h) and 4H-imidazo[4,5-b]pyridines (3a - 3c) was achieved by reacting 3,4-diaminopyridine or 2,3-diaminopyridine with NaSO adduct of corresponding benzaldehydes (a1 - a8). Alkylation of compounds (1a - 1h) and (3a - 3c) using 4-chlorobenzyl and /or butyl bromide under basic conditions (KCO, DMF) predominantly resulted in the formation of N regioisomers (2a - 2l) and N regioisomers (4a - 4c), respectively. The N-regioisomeric structures were confirmed using 2D-NOESY (Nuclear Overhauser Effect Spectroscopy) and HMBC (Heteronuclear Multiple Bond Correlation) spectra.