Synthesis and antifungal activity of diverse C-2 pyridinyl and pyridinylvinyl substituted quinolines

Diverse 2-pyridinyl quinolines 6-12 and 2-pyridinilvinyl quinolines 13-17 were prepared using a straightforward synthesis based on the BiCl3-catalyzed multicomponent imino Diels-Alder (imino DA) reaction or a novel tandem imino DA/catalytic tetrahydroquinoline ring oxidation/Perkin condensation sequential process. All members of the series showed activities against dermatophytes and some of them possessed a broad spectrum of action. 2-(Pyridin-4-yl)quinoline 9 and 2-(2-pyridin-4-yl)vinyl)quinoline 16 showed the best MIC80 and MIC50 against the clinically important fungi Candida albicans and non-albicans Candida species. In turn, 6-ethyl-2-(pyridin-2-yl)quinoline 6 showed the best properties against standardized as well as clinical strains of Cryptococcus neoformans.